金融商品取引法研究会研究記録
第 号 市場に対する詐欺に関する米国判例の動向について

48

公益財団法人 日本証券経済研究所

ISBN978-4-89032-664-8 C3032 ¥500E

金融商品取引法研究会
研究記録第 48 号

市場に対する詐欺に関する米国判例の動向について

公益財団法人 日本証券経済研究所
金融商品取引法研究会

市場に対する詐欺に関する米国判例の動向について（平成 26 年 11 月 26 日開催）
報告者

黒

沼

悦

郎

（早稲田大学大学院法務研究科教授）
目次

Ⅰ．はじめに…………………………………………………………………… 1
Ⅱ．34 年法規則 10ｂ−５の要件 …………………………………………… 2
Ⅲ．Basic 判決（1988 年） …………………………………………………… 3
Ⅳ．Halliburton Ⅰ判決（2011 年） ………………………………………… 5
Ⅴ．Amgen 判決（2013 年） ………………………………………………… 7
Ⅵ．Halliburton Ⅱ判決（2014 年） ………………………………………… 9
討議…………………………………………………………………………25

報告者レジュメ…………………………………………………………………42
資料…………………………………………………………………………58

i金融商品取引法研究会出席者（平成 26 年 11 月 26 日）

報 告 者 黒沼

悦郎

副 会 長 前 田 雅 弘
委員 飯 田 秀 総〃加 藤 貴 仁早稲田大学大学院法務研究科教授
京都大学大学院法学研究科教授
神戸大学大学院法学研究科准教授
東京大学大学院法学政治学研究科准教授

〃

神

作

裕

之

東京大学大学院法学政治学研究科教授

〃

中

東

正

文

名古屋大学大学院法学研究科教授

〃

中

村

聡

森・濱田松本法律事務所パートナー・弁護士

〃

山
事 萬

田
澤

志
子

成城大学法学部教授
専修大学法学部講師・当研究所客員研究員

幹オブザーバー
〃

剛
陽

〃

荻

野

明

彦

金融庁総務企画局市場課長
野村證券常務執行役員
兼チーフ・リーガル・オフィサー
大和証券グループ本社執行役員経営企画部長

〃

鎌

塚

正

人

ＳＭＢＣ日興証券法務部長

〃

田

島

浩

毅

三菱ＵＦＪモルガン・スタンレー証券法務部長

〃

高

良

美紀子

東京証券取引所総務部法務グループ課長

研 究 所 増井喜一郎

日本証券経済研究所理事長

前

忠

〃

田 原 泰 雄永 井 智 亮大日本証券経済研究所常務理事
（敬称略）

ii

市場に対する詐欺に関する米国判例の動向について
前田副会長

定刻になりましたので、第４回金融商品取引法研究会を始めさせていただきます。
本日は、会長の神田秀樹先生が司会をなされる予定でしたが、やむを得ないご事情でご欠席ですので、前田が司会をさせていただきます。
まず、人事異動に伴いまして、オブザーバーに変更がありましたのでご紹介させていただきます。今回より、SMBC 日興証券法務部長の鎌塚正人様にご参加いただくことになりました。どうぞよろしくお願いいたします。
既にご案内のとおり、本日は、早稲田大学の黒沼悦郎先生より「市場に対する詐欺に関する米国判例の動向について」というテーマでご報告をいただ
くことになっています。それでは、黒沼先生、よろしくお願いいたします。

［黒沼委員の報告］
黒沼委員

早稲田大学の黒沼でございます。

本日は、最近の米国判例３つを取り上げてご紹介し、また、学説の議論なども少し紹介したいと思っております。
お手元に配付資料として、その３つの判決の原文とレジュメを配付しておりますので、このレジュメに沿って話をしていきたいと思います。

Ⅰ．はじめにアメリカの判例を取り上げてどういう意味があるのかということなのです
けれども、１つには、アメリカに上場している日本企業もあって、その日本企業にとっては証券クラス・アクションは関心の高い対象だろうと思います。
もう１つは、日本には証券クラス・アクションはないわけですけれども、虚偽記載に基づく民事責任の追及が最近は盛んになっておりますので、その法理を考える上で参考になるのではと思います。

1

Ⅱ．34 年法規則 10ｂ−５の要件
早速内容に入っていきます。
34 年法規則 10ｂ‑５は、1934 年証券取引法 10 条（ｂ）項に基づいて、1942 年に SEC が制定した詐欺防止条項でありまして、判例はこの 10 条（ｂ）
項及び規則 10ｂ‑５、以下、総称して「Rule 10ｂ‑５」といいますが、これが私人が損害賠償を請求する根拠となること、すなわち私的訴訟原因が含意されていると認めてきました。もっとも、Rule 10ｂ‑５の文言からはその要件を読み取れませんので、判例はコモン・ロー上の詐欺の要件をかりて、私的訴訟原因の要件を判断してきました。判例によれば、私人が Rule 10ｂ‑５に基づいて損害賠償を得るには、「被告による重要な不実表示または省略」、「欺罔の意図」（scienter）、「不実表示または省略と証券の売買との関係」（inconnection with）、「不実表示または省略への信頼」（reliance）、「経済的損失」、「損害因果関係」（loss causation）を証明しなければなりません。
これらの要件のうち、重要性、信頼、損害因果関係及び経済的損失の要件
は、不実表示と損害賠償責任とを結ぶ重要な要件であり、原告が訴訟のどの段階でどの要件をどの程度証明しなければならないかが裁判で争われてきました。
最初に最高裁が取り上げたのは信頼の要件です。信頼とは「特定の原告が投資判断を行うにあたり、不実表示を重要な要素と考えたこと」を意味し、省略あるいは不開示と言ったほうがいいかもしれませんけれども、不開示の場合は「開示されなかった事実を知らされていたら原告が異なった行動をするような影響を受けたであろうこと」を意味します。信頼の要件は不実表示と原告の行為とを結ぶ因果関係なので、取引と損失を結ぶ損害因果関係に対して、取引因果関係とも呼ばれます。この点について判断したのが 1988 年の Basic 判決です。

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Ⅲ．Basic 判決（1988 年）（Basic Inc., v. Levinson, 485 U. S. 224（1988）. 解説として、拙稿「会社情報の開示と民事責任― Basic 判決を中心として―」名古屋大学法政論集 133
号（1990）1 頁。）【事実】
Basic 社が合併の交渉中であるという事実を隠し、合併交渉をしていな
いとの声明を発表したことに対し、Basic 社株を売却した株主が会社及び取締役の責任を追及するクラス・アクションを提起した。
連邦民事訴訟規則 23 条（ｂ）項（３）号によると、個々の原告に関する個別の問題よりも、クラスに共通の法律問題または事実問題が支配的でなければクラスの認可は認められないところ、連邦地方裁判所は信頼の推定を認めクラスを認可した。第７巡回区控訴裁判所はクラス認可を維持したので、最高裁は、合併交渉に適用される重要性の基準がいかにあるべきかということともに、クラスの認定の際に、裁判所が表示に対する直接的な信頼をクラス・メンバーに要求せず、信頼の推定を及ぼしたことが適切かどうかについて裁量上訴を認めた。
以下、レジュメに掲げた判旨は、要約かつ意訳をしたものでありますので、その点ご注意ください。
【判旨】
法廷意見
市場に対する詐欺理論（fraud on the market theory）とは、公開市場において会社の株価は、会社およびその事業に関する情報に基づいて決定されるとの前提に立ち、原告が不実表示に直接依拠しなかった場合でも、被告の不実開示と原告の証券購入との間の因果関係を認める理論である。
我々の仕事は、市場に対する詐欺理論の有効性を一般的に評価することで3

はなく、裁判所が、部分的に市場に対する詐欺理論に依拠して、信頼の反証可能な推定を認めたことが適当かどうかを考察することにある。
原告に、開示されなかった事実が開示されたとしたら、あるいは、不実表示がなかったとしたら、どのように行動していたかを立証させることは、公開市場で取引をした原告に、不必要かつ非現実的な立証責任を課すことになる。信頼の推定は、公正、公序、蓋然性、および訴訟経済の観点から見ても、当事者間で立証責任を分配する有用な方法である。本件で採用された信頼の推定は、Rule 10ｂ‑５訴訟を促進することになるが、それは、証券市場の誠実性（integrity）に対する投資者の信頼を促進するという1934 年法の立法政策とも整合的である。
推定は、コモンセンスおよび蓋然性からも支えられている。最近の実証研究は、高度に発達した市場で取引される株式の市場価格が、すべての公開情報を反映しており、したがって、重要な不実表示をも反映していることを示している。…市場で形成された価格で株式を売買する投資者は、当該価格の誠実性を信頼して売買を行っている。多くの（most）公開情報
は市場価格に反映されているから、公開された重要な不実表示に対する投資者の信頼は、Rule 10ｂ‑５訴訟の関係において、推定されうるのである。
【White 判事、O Connor 判事の反対意見】
経済理論を法原則に取り入れるとしても、それは、裁判所よりも専門家の助けを得ることのできる議会が、法律改正によって行うべきである。
投資者が「株価をその株式の価値を反映するものとして信頼していること」は疑問である。多くの投資者は、株価が会社の価値を反映していないと信じるからこそ株式の売買を行うのではないか。
市場に対する詐欺理論は、34 年法 18 条（ａ）項が要求する厳格な信頼の要件を骨抜きにする点、および情報をみない投資者を保護する点で、34年法の立法目的に反している。

4

この Basic 判決は、当該事件の控訴裁判所が採用した「推定」を適切であるとし、推定が認められるための要件を明示していませんが、控訴審では、推定が認められるためには、原告は、（１）被告の不実表示が公表されていること、（２）不実表示が重要であること、（３）株式が効率的な市場で取引されていること、（４）不実表示が、投資家に株式の価値を誤って評価されるものであること、（５）原告が、不実表示がなされてから真実が発覚するまでの間に株式の取引を行ったことを主張し、証明しなければならないとします。ただし、（４）については、後の判例では要件から除外されていて、通常４つの要件が必要だと言われています。
これを前提に判決は、「不実表示と原告の受け取った（または支払った）価格との間の繋がり、または不実表示と市場価格で取引を行うという原告の決定との間の繋がりを断ち切るいかなる証明も、信頼の推定を覆す」として、推定が覆される例として、①マーケット・メーカーが真実を知っており、市場価格が不実表示の影響を受けなかった場合、②真実の情報が市場に到達しており、不実表示の影響を打ち消していた場合、③原告は、市場の誠実性を信じたのでなく、他の理由で取引を行った場合を挙げています。

Ⅳ．Halliburton Ⅰ判決（2011 年）（Erica P. John Fund, Inc. v. Halliburton Co., 131 S. Ct. 2179（2011）. 解説
として、藤林大地「市場における詐欺理論の適用と損害因果関係の立証の要否」商事 1979 号（2012）53 頁。）【事実】
EPJ Fund が、Halliburton 社が、アスベスト訴訟の潜在的な範囲、ある建設契約から生じる予想収益、及び他の会社との合併の便益について、故意にさまざまな虚偽の開示を行ったと主張して、1999 年６月３日から2001 年 12 月７日までにＨ社の株式を購入した者を代表してクラス・アクションを提起した。
却下の申立て（motion to dismiss）を退けたのち、地方裁判所は、EPJ
5

Fund は、請求に係る損害因果関係を証明しておらず、連邦民事訴訟規則23 条（ｂ）項（３）号の要件を満たさないとして、クラスの認可を拒絶した。第５巡回区の先例は、クラス認可を得るために、原告は損害因果関係の証明をしなければならないと求めていたからである。そこで、クラス認可のために損害因果関係の立証が必要かどうか、巡回区レベルで裁判例が一致していなかったので、その不一致を解消するために、最高裁が裁量上訴を認めた。
【判旨】 破棄差戻し。
本件下級審は、クラス認可における共通性の要件を充たすために、信頼の立証が必要であり、信頼の証明のためには損害因果関係の証明が必要と考えた。
しかし、控訴裁判所の要件は、Basic 判決の論理からは正当化されない。
損害因果関係は、投資家が不実表示を信頼したか否かとは関係のない事柄
に関するものである。後の損失が不実表示の発覚以外の要因によって生じたという事実は、投資家が最初の段階で不実表示を信頼したかどうか（それが直接であれ、推定される場合であれ）とは関係がない。
Halliburton は、本件下級審が損害因果関係の名の下で実際に問うたのは、主張された不実表示が最初の段階で市場価格に影響を与えたか、すな
わち価格影響性（price impact）の有無であったと主張する。しかし、控訴裁判所が言おうとしたことを Halliburton がどう考えるにせよ、実際に言ったのは損害因果関係である。
判決の内容は当然のようにも思えるのですが、これは Amgen 判決やHalliburton Ⅱ判決への伏線となっていて、実はそう単純な問題ではないということが後でわかります。

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Ⅴ．Amgen 判決（2013 年）（Amgen Inc. v. Connecticut Retirement Plans and Trust Funds, 133 S.
Ct. 1184（2013）. 解説として、藤林大地「証券集団訴訟の認可と不実表示の重要性の立証の要否」商事 2015 号（2013）38 頁。）【事実】コネチカット州の退職年金ファンドが、バイオテック会社 Amgen とその役員（併せて Amgen という）に対し、証券クラス・アクションを提起し、信頼の要件については「市場に対する詐欺」推定を援用し、クラス・アクションの認可を求めた。地裁はクラスを認可し、第９巡回区控訴裁判所は、退職ファンドはクラス認可の前に虚偽記載または省略の重要性を証明する必要があるとの Amgen の主張を退け、クラスの認可を維持した。同裁判
所は、また、クラス認可の段階で Amgen が提出した、重要性の反証となる証拠を考慮することを地裁が拒絶した点に誤りはなかったと判示した。
最高裁は、クラス認可のために重要性を立証する必要があるかどうかについて、巡回区の不一致を解消するために、裁量上訴を認めた。
【判旨】
重要な問題は、クラスに共通する法または事実の問題が、個々のメンバー
のみに影響する問題に対して支配的であるといえるためには、重要性の証明が必要かどうかである。その答えは２つの理由により「否」である。
第１に、重要性は客観的な基準に従って判断できるので、クラスに共通の証拠によって証明され得るからである。したがって、重要性は、23 条（ｂ）
項（３）号にいう「共通の問題」（common question）である。
第２に、原告が略式判決の申立てや本案において、重要性の十分な証拠を提出できなかったときは、個々人の信頼の問題がクラスに共通の問題に優越するという事態を招くことはない。重要性の要件の証明に失敗したと
きには、すべての者にとって訴訟は終了し、個々人の信頼という争点が支7

配的になるような請求が残ることはない。
Amgen は、市場に対する詐欺理論の前提条件はクラス認可の前に充たされなければならないから、前提条件の一つである重要性もクラス認可の前に証明されなければならないという。しかし、重要性と異なり、市場の効率性および不実表示が公表されたことは、Rule 10ｂ‑５の欠くことのできない要素ではない。後２者が証明されなくても、信頼の個別的立証が許されるが、重要性が証明されなければクラスの請求全部が棄却される。市場の効率性や公表の争点と異なり、重要性の争点が証明できなければ、個別問題が共通問題に優越することはないので、重要性は 23 条（ｂ）項（３）号のクラス認可の前に証明される必要はない。
Amgen は、クラス認可は和解への大きな圧力となるから、認可前に重要性を争えないと、重要性を争う場面がなくなると主張する。しかし、その点は、不実表示や損害因果関係の要件についても同じである。議会は和解の圧力に対して、クラス認可段階で重要性の証明を求めること以外の手
段によって対処したのであり、これに加えて裁判所が 23 条（ｂ）項（３）号の再解釈により調整を行う必要はない。
Amgen は、原告の申立てに対して、重要性の反証を提出できないとした点に地裁判決の誤りがあると主張する。しかし、主張された不実表示が最終的に重要でないとされる可能性があることは、共通問題が支配的であることを妨げるものではない。本件の地方裁判所が、Amgen の反証の考
慮を略式判決または事実審（トライアル）にとっておいたのは正しい。
本判決では、Thomas 判事が反対意見を記載し、Kennedy 判事がこれに同調、Scalia 判事もその一部に同調しています。
解説を加えておきますと、不実表示の重要性は、市場に対する詐欺理論による信頼の推定を認める要件の１つなのに、クラス認可の段階で証明を要しないのはなぜか。判決はこの問題に対して、重要性が客観的証拠によって証明できるという点で共通の問題であること、仮に本案において重要性が証明
8

されなかった場合には訴訟は終了するので、改めてクラスの認可を判断する必要がないことをもって答えています。
クラス認可の段階で重要性の証明が不要だとすると、被告は重要性を反証する証拠を提出できないという不利益を受けるわけですが、裁判所はそれもやむを得ないと考えたわけです。ただ、この点は Halliburton Ⅱ判決で、実質的に一部変更されたと見る余地もあるように思います。

Ⅵ．Halliburton Ⅱ判決（2014 年）（Halliburton Co. v. Erica P. John Fund, Inc., 134 S. Ct. 2398（2014）. 解説
として、池谷誠「Halliburton 事件最高裁判決の検討」商事 2042 号（2014）
41 頁。
）
【事実】
Halliburton Ｉの差戻審において、被告は、損害因果関係の反証として提出していた証拠は、不実表示が価格に影響を与えていなかったことの証拠であると主張した。地裁は Halliburton の主張を取り上げることを拒否し、第５巡回区控訴裁判所も、価格影響性（price impact）の反証は事実審のみで認められるとした。最高裁は、① Basic 判決の信頼の推定を覆したり、修正したりすべきかどうか、②もし修正しない場合、被告は、クラス認可の段階で、価格影響性の欠如を証明することにより、推定を反証す
る機会を与えられるべきかどうかの２点について、裁量上訴を認めた。
【判旨】（市場に対する詐欺に関連しない部分は紹介を省略）【法廷意見】 Roberts 判事ほか６名の裁判官
１

信頼の推定法理の維持
Halliburton は、Basic 判決の２つの前提が今日では成り立たないので、判例が変更されるべきだと主張する。
第 １ に、 今 日 で は、 効 率 的 資 本 市 場 仮 説（eﬃcient capital market
9hypothesis）が成り立たない証拠がいくらであるという。たしかに、ある証券についての市場は他の証券についての市場よりもより効率的であり、ある一つの市場も、種類の異なる情報に対しては、より効率的であったり、効率的でなかったりする。
Halliburton は、市場の株価が会社の公開情報を反映する程度に関する経済学者の議論に焦点を当てるが、Basic 判決の裁判所は議論があることは認めており、信頼の推定を認めることは、公開情報がどれだけ早く正確に反映するかについての特定の理論を採用することを意味するものではな
いと述べている。裁判所は、一般的にいって、市場のプロが、会社に関する公表された重要な情報、従って市場価格に影響を与えるような情報の多くを（most）考慮しているという穏健な前提を置いているだけである。
Halliburton が引用する学説は、このような穏健な前提を否定するものではない。
第２に、Halliburton は、投資者が市場価格の誠実性（integrity）を信頼して投資を行うという、Basic 判決が仮定に置いている命題を攻撃する。
Halliburton は多くの例を引用するが、そのうち重要なのは、株式が過小
評 価 ま た は 過 大 評 価 さ れ て い る と 信 じ て い る バ リ ュ ー 投 資 家（value
investor）であろう。しかし、Basic 判決はバリュー投資家の存在を否定するものではない。そのような投資家は、株価が最終的には重要な情報を反映すると暗黙のうちに信頼しているのである。（そのような市場修正がないとしたら、どうやってバリュー投資家は利益を得るのか？）。たしかに、
バリュー投資家は取引の時には価格を信頼していない。しかし、信頼の推定を受けるためには、合理的な期間内に市場が情報を反映すると信じていれば足りる。
Halliburton およびその賛同者は、Basic 判決は、証券クラス・アクショ
ンを促進することにより、深刻で害のある結果を引き起こしてきたと主張する。しかし、そのような心配は議会によって対応されるべきものであり、
すでに 1995 年の私的証券訴訟改革法によって対処されてきた。
10

２

クラス認可段階における反証
Halliburton は、Basic 判決を変更する２つの提案をしている。

第１は、信頼の推定を発動させるために、原告は、不実表示の価格影響性を証明しなければならないというものである。たしかに、Basic 判決が採用した信頼推定の４つの要件（公表、重要性、市場の効率性、取引の時期）のうち、前３者は価格影響性に向けられたものである。しかし、Basic 判決の信頼推定の要件は２つの構成要素からなる。第１に、原告が、不実表示が公表されており、重要であり、かつ原告が、一般的に効率的な市場で取引をしたことを証明した場合には、彼は不実表示が価格に影響を与えたとの推定を受けることができる。第２に、原告が、関連する期間に市場価格で株式を購入したことを証明した場合には、彼は不実表示を信頼して株式を取得したとの推定を受けることができる。原告が価格影響性を直接に証明しなければならないという Halliburton の提案は、第１の構成要素を原告から奪うことになる。市場の効率性はあるかないかの命題ではないから、一般的に効率的な市場において、重要な不実表示が株価に影響を与えないこともあり得る。だからこそ、Basic 判決は、特定の不実表示
が価格に影響を与えなかったという反論の機会を被告に与えている。我々は、Basic 判決を半分廃棄することになる原告の主張を認めることはできない。
第２に、Halliburton は、クラス認可段階で、不実表示が株価に影響を与えなかったという証拠により、推定を覆すことを認めるべきだと提案する。我々はこの提案に賛成する。
従来から、クラス認可の段階で被告が価格影響性を否定する証拠を提出することは、それが、推定の反証ではなく、市場の効率性を反証する目的を持つ限り、認められてきた。しかし、このような制限は意味がなく、奇妙な結果を招く。たとえば、クラス認可の段階で、被告が６つのイベント
に関するイベント・スタディを提示し、そのうちの１つが被告の不実表示であったとする。地裁が、市場は効率的であったが、不実表示に対しては
11

市場の反応がなかったと認定した場合、これは信頼の推定を覆すものではないという理由でクラスを認可することはおかしい。
このようなおかしな結果は Basic 判決の論理とも矛盾する。Basic 判決の市場に対する詐欺理論の下で、信頼の推定を発動させる市場の効率性と他の前提条件は、価格影響性を間接的に証明するものである。そうだとす
れば、被告には、価格影響性の直接的な反証を認めるべきである。
控訴裁判所は、Amgen 判決に依拠して、Halliburton はクラス認可の段
階で価格影響性の反証を提出できないと判断した。しかし、Amgen 判決は、
クラス認可の段階で原告が重要性を証明しなければならないかどうかについて判示したものである。重要性は Basic 判決の推定の前提条件であるが、それは連邦民訴訟事規則 23 条（ａ）項（３）号の支配性の要件と関連しないので、本案まで持ち越されると我々は判示した。EPJ Fund は、価格影響性の要件も重要性の要件と同じあるという。しかし、価格影響性は重要性と重要な点で異なる。価格影響性は、Basic 判決の基本的な前提であり、クラス認可段階の支配性の争点と深く関係している。
他の要件がクラス認可の段階で証明されているのであれば、クラスに共通する要件である重要性を本案段階に持ち越したとしても、クラスの認可をあとで覆すような事態には至らない。これに対し、価格影響性について
は、クラス認可段階ですでに間接的な証拠が提示されているのであり、クラス認可段階で、直接的な証拠による価格影響性の反証を認めない理由はない。
【Ginsburg 判事、Breyer 判事、Sotomayor 判事による賛成意見】
価格影響性の考慮を本案段階からクラス認可へ早めることは、認可段階で利用できるディスカバリーの範囲を拡げることになる。もっとも、価格影響性がないことの立証責任は被告が負うので、本判決は証券訴訟の原告に追加的負担を課すものではない。以上の理解を前提として法廷意見に賛成する。
12

【Thomas 判事、Scalia 判事、Alito 判事の意見（実質的反対意見】
Basic 判決による信頼の推定は誤りであった。その理由は第１に、裁判所が、争いのある経済理論と投資家の行動についての誤った直観に依拠したからであり、第２に、それが、クラス認可を求める原告に、個別の争点
より共通の争点が支配的であるという要件の立証を求める連邦民事訴訟規則 23 条に関する判例法に反するからである。第３に、推定された信頼は、ほとんど反証することが不可能であり、信頼の要件を廃止するのに等しいからである。
Basic 判決が前提とする事実のうち、公表情報が市場価格に反映されているという点は、効率的資本市場仮説に立脚したものであるが、Basic 判
決以来、その経済理論は広く批判にさらされている。また、市場が公表情報を反映するにしても、正確に反映するとは限らないことを示す多くの実証研究がある。
Basic 判決が前提とするもう一つの事実、すなわち投資家は市場の誠実性を信頼しているという点は、誤りであり。多くの投資家は、市場が株式を過大評価または過小評価していると信じているからこそ、取引をしているのであるし、他の投資家は、価格と関係のない理由で、たとえば流動性の需要、税金の考慮、ポートフォリオの組換えのために取引している。
多数意見は、穏健な前提を置くことで理論と現実を架橋しようとする。
しかし、そのような穏健な前提は、Basic 判決の判決文言と整合しない。
また、多数意見は、市場が過大評価・過小評価しているバリュー投資家も、
将来、市場価格が公表情報を反映することを信じているというが、取引の際に市場価格が公表情報を反映していなければ、投資家は、公表情報が彼を取引に誘い込んだと主張することはできないはずである。
Basic 判決は、被告に反証の機会を与えているようにみえる。しかし、クラス認可の段階では、反証はクラス代表に対してのみ、なされるので、クラス代表の信頼を反証することは難しい。クラス認可後は、裁判所は信頼の要件の反証を拒絶してきた。信頼の反証を認めた事例は、何千もの
13

Rule 10ｂ‑５訴訟中６件しかないという。Basic 判決は、信頼の要件を実質的に廃棄するのに等しい。
そこで、解説といいますか、コメントに近いことを述べます。
１

信頼の推定

（１）効率的資本市場仮説に依拠するものでないこと
Basic 判決が出された 1988 年以降、情報に対する証券市場の効率性については、疑義を呈する実証研究が多数公表されており、市場に対する詐欺理論の基礎が揺らいできました。多数意見は、市場に対する詐欺理論は、市場の効率性を前提とするものではないとして Basic 判決を維持しました。
Basic 判決が特定の経済理論に依拠しているものでないことは確かにそのとおりです。しかし、「市場の効率性」は依然として信頼の推定のための要件の１つとされているわけであります。本判決によっても、その立場は変更されていません。
学説では、Basic 判決は、市場に対する詐欺理論と効率的市場仮説を結びつけたけれど、本来、ある証券の市場価格が詐欺情報を反映している限り、市場に対する詐欺理論により信頼を推定するために、証券市場が一般的に効率的であることを示す必要がないという点は比較的早くから指摘されてきました（Jonathan R. Macey et al., Lessons from Financial Economics:
Materiality, Reliance, and Extending the Reach of Basic v. Levinson, 77 Va. L.
Rev. 1017, 1021（1991）等）。Halliburton Ｉ及び Halliburton Ⅱでは、多くの学者が裁判所の友（amici curiae）として意見を寄せていますが、それらの多くも、裁判所は市場が効率的であるかどうかではなく、特定の不実表示
が市場価格に影響を与えたかどうかに着目すべきであるとしています。
（２）Bebchuk & Ferrell の見解
ここでは、市場の効率性と信頼の推定との関係を例証しようとしている
14

Bebchuk と Ferrell の論稿（Lucian A. Bebchuk & Allen Ferrell, Rethinking
Basic, 69 Bus. Law. 671（2014））、これは 2014 年６月に公表されて、この判決に間に合わなかったようですが、それ以前に SSR Ｎにその草稿が載っていて、多くの学者の意見もこれに依拠しているもので、最も詳しいということから、これを紹介したいと思います。
この論文では次のようなことが述べられています。
一般に、市場は、利益を得る裁定機会（arbitrage opportunity）がない
場合に効率的であると定義されてきた。
し か し、 第 １ に、 裁 定 機 会 の 存 在 は、 詐 欺 に よ る 市 場 価 格 の 歪 曲（fraudulent distortion）の存在を否定するものではない（市場が効率的でなくても、詐欺による市場価格の歪曲は起こり得る）。
市場の効率性は３つの分野で争われてきた。①市場は長期的な収益を過大評価している。②過剰なボラティリティ、③情報に対する市場の反応の鈍さ、である。
まず、過大評価設例として、次のような例が挙げられています。
市場の株価収益率が歴史的に 15 倍であったところ、現在、市場が長期的収益を過大評価し、20 倍となっていた。企業が収益を１ドルのところ２ドルと不実表示した。株価は 20 ドルから 40 ドルに上昇し、不実表示の発覚により株価は 20 ドルに戻った。その後、市場は長期的な過大評価を修正し、株価収益率は 15 倍に戻り、株価は 15 ドルとなった。クラスワイ
ドな信頼を認めるかどうかにとって、不実表示によって株価が上昇したことが重要であり、株価収益率が過大評価されていたかどうかは関係がないのは、この例を見れば明らかではないか。
次に、過剰なボラティリティの設例です。
上の例で、株価が 20 ドルから 40 ドルへ上昇した。過剰なボラティリティのせいで、株価は、１時間ごとにランダムに 38 ドルから 42 ドルの間で変動していた。不実表示の発覚により株価は 20 ドルに戻ったが、同じ理由で、
15

19 ドルから 21 ドルの間で変動していた。クラスワイドな信頼を認めるかどうかについて、過剰なボラティリティの有無は関係がない。たしかに過剰なボラティリティは利益の機会を生じるが、不実表示によって価格が歪められていたことに変わりはない。
３つ目は、鈍い市場反応設例です。
上の例で、良い情報に接して株価は 20 ドルから 35 ドルに上昇したが、翌週１週間かけて 40 ドルまで上昇した。不実表示が発覚すると株価は 20ドルに戻った。不実表示の開示を受けて当該株式を取得した者が、市場価格の歪みの結果、15 ドルないし 20 ドル余分に支払った事実には変わりがない。
反応が遅いために、裁定の機会があったとしても、因果関係は認められるはずであるというわけです。
第２に、裁定機会がない、すなわち市場が効率的であることは、不実表
示が市場価格の歪みをもたらさない場合があること否定するものではないとして、２つの例を挙げています。この例はややわかりにくくて、私も十分理解しているとは言えないんですけれども、議論の材料になるかと思ってご紹介するところです。
第１は公表された情報の設例であります。
インターネット企業が、四半期収益を公表した。その数日後、サイトへの来訪者数が 75％上昇したとの不実表示を公表した。アナリストは来訪者数の情報を分析して、それが企業の収益性に与える影響を分析した。不実表示を公表したときも、それが不実であると発覚したときも株価に変化はなかった。
この場合、価格の歪みがないからクラスワイドな信頼は与えられない。
市場が開示情報に反応しなかった理由（情報が重要でなかった、四半期収益の情報で株価が決定されていた、市場が虚偽情報を信頼していなかった等）はなんであれ、重要なのは市場価格に歪みが生じたかどうかである。
第２は、埋没した情報設例です。
16

企業が、環境政策に関する公表された報告書（投資家の興味を惹かなかった）の中で、財務情報について不実表示をした。不実表示をしたときも、その発覚のときも、市場価格に変化はなかった。
クラスワイドな信頼は与えられない。情報が価格に反映されなかった理由は重要でない。重要なのは市場価格の歪みが生じていないこと。
Bebchuk & Ferrell は、今の例を含めていろいろな議論をした後に、信頼の推定法理は次のように改訂されるべきであるとしました。レジュメで二重取り消しがかかっているところは削除すべきところで、太字のところは追加
すべきところという意味です。
変更後の法理というのは、（１）市場で取引されている市場の価格は、公開され利用可能な会社に関するいくつかの情報を反映する。全てではなくてsome ということです。（２）したがって、市場における市場の買主は、購入するに際して、当該市場価格が詐欺的に歪められていないことを、たとえば、不実表示がなかったとしても異なる価格ではないことを信頼したと推定されることができる。（３）そして、証券の市場が詐欺的に歪められていな
いとき、原告はクラスワイドな信頼の推定を起動させることができない。
（３） 判旨の検討
Halliburton Ⅱ判決は、判旨２で価格影響性（price impact）という概念を用いましたが、これは今紹介した Bebchuk & Ferrell の言うところの詐欺による歪曲と同義だろうと思います。多くの学説が主張するように、最高裁は、市場に対する詐欺理論を市場の効率性を価格影響性に置きかえたものに修正すべきだったと思います。しかし、判例を変更しなくても信頼の推定を認めるという結論には変わりがないので、最高裁は Basic 判決の修正を避けたものと思われます。
この結果、Halliburton Ⅱ判決によると、信頼の推定を受けるためには、市場が効率的であることを依然として原告側が示す必要があります。一般に
17

市場の効率性の証明方法としては、Cammer 判決（Cammer v. Bloom, 711 F.
Supp. 1264（1989））の示した５要因テストが用いられていると言われており、そこでは株式の取引量、当該株式をフォローしていたアナリストの数、マーケット・メーカーの数、Ｓ‑３の登録要件を充たすかどうか、予期しない新事象に対する株価の反応を基準として、当該株式の市場が効率的であるか否かが決定されています。裁判実務上、このような効率性の検証が引き続き行われるようであれば、それは学説から批判される余地があろうかと思います。
（４）市場の誠実性に対する信頼というレトリック
法廷意見は、バリュー投資家も、いずれは市場価格が情報を反映すると考えて投資しているから、市場の誠実性を信頼していると説明しています。これに対し反対意見は、バリュー投資家が取引のときに市場の誠実性を信頼していたかどうかが問題なのだとします。
この議論は反対意見に分があります。ただ、そもそも市場の誠実性に対する信頼を問題にすること自体、レトリックにすぎないと思われます。バリュー
投資家は、効率的でない市場の投資家像を反映したものであり、現実の市場には、市場価格が情報を反映していると考えて取引を行う投資家と、そう考
えないがゆえに取引を行う投資家が併存することは否定できません。いずれの投資家についても、不実表示によって影響を受けた市場価格で取引を行えば、不実表示と取引との間の因果関係が認められると理解すれば足ります。
最高裁は、市場の効率性を前提とするという理解のもとで Basic 判決を変更しなかったので、こういったレトリックを用いざるを得なかったわけです。
２

クラス認可段階での価格影響性の反証（１）価格影響性と損害因果関係
多数意見は、価格影響性という概念を用いて、価格影響性は重要性と異なり、クラス認可段階で反証可能であるとしました。果たして、価格影響性は
18

重要性と異なるのか。また、損害因果関係とは異なるのかということが問題になります。
まず、損害因果関係との関係です。損害因果関係というのは、投資家の取引と、彼がこうむった損失との間の因果関係のことをいいます。正確には「損失因果関係」と訳したほうがいいのかもしれないのですが、私もずっと損害因果関係と訳しており、何となくそれが定着していますので、ここでは「損害因果関係」という言葉を使っています。
損害因果関係があると言えるためには、有価証券の取得時に不実表示によって市場価格が不当につり上げられていたことを証明するのでは足りないとするのが判決（Dura 判決、Dura Pharmaceuticals, Inc. v. Broudo, 544 U. S.
336（2005））であり、不実表示の発覚が株価を下落させたことを示すことは、損害因果関係の立証の一方法と考えられています。
また、価格影響性とは「被告の不実表示が実際に株価に影響を与えたか」ということですが、これも不実表示がされた時点のイベント・スタディを行うことは難しいことが多いので、不実表示の発覚時のイベント・スタディにより確認することになるでしょう。そうすると、価格影響性と損害因果関係とは実は同じ問題ではないかと思われます。
Coﬀee 教授は、コロンビア大学のホームページで公開されているブログの中で次のように述べています（John C. Coﬀee Jr., Death by One Thousand
Cuts , Columbia Law School s Blog on Corporations and the CapitalMarkets（June 30, 2014）,at http://clsbluesky.law.columbia.edu/2014/06/30/
death-by-one-thousand-cuts/）。
「Halliburton Ｉは、損害因果関係はクラス認可の段階では争えないとした。
Halliburton Ⅱは、これを実質的に変更して、『価格影響性』はクラス認可段
階で争えるとした。同じ証拠が損害因果関係の反証にも価格影響性の反証にも使えるのだから、法はいつもラベル貼りの問題である」。
Fox 教授も同じ媒体でコメントを公表しているのですが、「価格影響性と損害因果関係とは実質的に同じ争点である」とします（Merritt B. Fox,
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Halliburton II: Who Won and Who Lost All Depends on What Defendants
Need to Show to Establish No Impact on Price , Columbia Law School s
Blog on Corporations and the Capital Markets（June 30, 2014）, at http://
clsbluesky.law.columbia.edu/2014/06/30/halliburton-ii-who-won-and-wholost-all-depends-on-what-defendants-need-to-show-to-establish-no-impact-onprice/）。
これに対し、Bebchuk & Ferrell は例を挙げて、価格影響性、彼らの言うところの詐欺的歪曲と損害因果関係とは異なるとします。
FDA 承認設例
企業が、FDA（アメリカ食品医薬品局）が医療機器を承認するだろうという虚偽の公表をした。株価は直ちに 10％上昇した。原告は、不実表
示が市場価格に影響を与えたことを証明した。
この場合、クラスワイドな信頼は認められる。しかし、詐欺的歪曲が経済損失を生じさせたことはまだ証明されていない。Dura 判決は、価格のつり上げだけでは経済損失の近因にならないとする。価格影響性は、損害因果関係の必要条件であるが十分条件ではない。
もっとも、この例は不実表示時のイベント・スタディで詐欺的歪曲を証明できる事例を前提としており、重要な事実を隠した場合、これは不開示に限らず、虚偽記載の場合でもそういった例はありますが、両者は同じではないかという疑問はなお残るように思います。
（２）価格影響性の反証の程度
次に重要なのは、クラス認可の段階でどの程度の反証の負担があるのかという点です。
Coﬀee 教授は、先ほどのブログで次のような問題を設定しています。例えば「訂正情報の開示の際に市場価格が下落したが、その有意性は、通常求め20られる 95％のレベルではなく 90％のレベルであった。被告は、価格影響性を反証したと認められるか？」。
Fox 教授も、実質同じ問題について述べているのですが、その表現が違うので紹介します。
「クラス認可段階での被告による価格影響性の反証について、本案段階での原告による損害因果関係の立証と同程度のものを求めるとしたら、被告の反証権は意味のないものとなる。すなわち、95％の信頼水準を要求するのでは意味がない。これに対し、原告が損害因果関係の立証ができないであろうことを被告が裁判所に説得することだけで、信頼の推定が反証されるのだとしたら、本判決は被告にとって意味がある。この場合には、価格影響性と実質的に同じ争点である損害因果関係を、クラス認可の段階で、被告に立証責任を負わせて行うことになる」。
これは、立証責任が転換されているということを表現したものだろうと思います。その限りで、反証の程度も本案段階の原告による証明と同程度のものは求められないだろうということです。
価格影響性の反証の程度の問題は、今後下級審判例に委ねられた課題であると言えます。
（３）不開示の場合とのバランス
発行者等が開示すべき情報を開示しなかった不開示の場合には、厳格な信頼の要件を課すと、原告は不開示の対象について、それが存在しないと信頼したことを立証しなければならないけれども、その証明はほとんど不可能です。そこで、判例は開示義務の存在と秘匿された事実の重要性の要件が満たされるならば、因果関係の要件は充足されるとしました（Aﬃliated Ute
Citizens v. United States, 406 U. S. 128（1972））。
この事件は対面取引の事例でしたが、その後の裁判例は、公開市場取引についても、不開示の場合には信頼の要件は不要である旨判示しています。このように不開示の場合には信頼の要件の充足が不要であり、クラス認可が認
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められるとすると、積極的な不実表示の場合に、クラス認可段階で価格影響性の反証が認められることとのバランスが問題になります。
Bebchuk & Ferrell は、詐欺的歪曲の有無を基準とするアプローチを不開示の場合に適用しない理由はなく、統一的なアプローチをとることで、不実表示と不開示のどちらに当たるかという恣意的な区分を解消することになるとします。不開示の場合には、ある事実が開示されなかったことが市場価格に影響を及ぼし、投資家の取引の原因となっているわけですから、価格影響性の反証も認められるべきでしょう。
（４）価格影響性と重要性
重要性とは、合理的な投資家が投資判断に当たって、当該表示を重要と考えたことを意味し、重要と考えたかどうかは、当時利用可能な情報の総体を大きく変えるかどうかで判断されます。情報が重要であれば市場価格に影響を与えますから、価格影響性と重要性の異同が問題になります。本判決は価格影響性と重要性とは異なるとしますが、判旨が掲げる価格影響性と重要性の相違は、性質の相違というよりもクラス認可の段階で証拠が提出されているかどうかの相違にすぎず、理由づけとして余り説得的でないように思います。
Bebchuk & Ferrell は、価格影響性と重要性とは異なり、価格影響性の反証を認めることは重要性の要件の審理を先取りすることにはならないとして、次の例を挙げます。
鉱山設例
アメリカの鉱山会社がオーストラリアに金鉱を所有している。CEO が鉱山を訪れ、鉱山技師と会話をし、帰国後、「鉱山技師と会話をした。金鉱はとても良いと思う（feel great about the gold mine）」と発言した。
株価は 10％上昇した。後になって、当該金鉱で金を産出することが不可能であると判明した。原告は、CEO の虚偽発言と市場に対するインパク
22

トを証明した。
クラスワイドな信頼は認められる。しかし、本案の段階で、被告は表示の重要性を争う余地がある。なぜなら、事実の争点は、技師が CEO に話した内容はなにか、その内容（情報）は金鉱をどれだけ有望なものにする
か、その情報は CEO の発言を導いたかといった点にあるから。市場に対する影響度と、表示が重要な点で誤解を生じるものを含んでいたかどうかは別問題である。
この設例と説明が説得的であるかどうかよくわからないので、ご意見を伺えれば幸いです。
３

クラス・アクションへの影響以上が判決そのものの検討ですが、その影響について簡単に述べたいと思います。
クラス・アクションへの影響が一番重要な点だと思いますが、アメリカでも余り資料が公表されていないので、議論の状況はよくはわかりません。以下では、私が知り得たところのみを述べます。
従来、NYSE や Nasdaq で取引されている株式に関するクラス・アクショ
ンでは、クラス認可は自動的に与えられてきました。こういった市場は一般的に効率的であると認められるからです。ところが、クラス認可段階で、被告は価格影響性を争えるようになるため、クラス認可段階がミニ・トライア
ル化すると言われています。クラス認可の段階でも、資料として専門家の証言を提出するなどディスカバリー類似の手続が行われるようです。
この結果、原告の費用負担は増え、訴訟は減少する可能性があります。
被告は、①棄却の申立て（motion to dismiss）、②クラス認可の申立て、③略式判決の申立ての３段階で争うことができるようになる。従来、証券ク
ラス・アクションは略式判決申立ての前後で和解になることが多かったが、それよりも前で争うことが可能になったということです。
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以上は、主として Coﬀee 教授の前記コメントによるものです。
また、別の実務家が書いたものでは、D&O 保険について触れています。
「被告が価格影響性を争えるので、保険者の支払件数は減少するだろうが、価格影響性をめぐる争いが防御費用を増加させるだろう。保険業界において、クラス認可段階における価格影響性のイベント・スタディの費用を付保範囲とすべきについて議論がされるだろう」。
４

日本法への示唆
日本法に照らすと、信頼の要件及び損害因果関係の要件は、相当因果関係の一部をなすものであり、不実表示の重要性という要件も相当因果関係に関連するものです。また、明文で信頼の要件を課す条文は日本にはなく、証券
クラス・アクション制度もありませんので、クラス・アクションの認可との関係で信頼の要件が問題とされるということもありません。
もっとも、不実表示に基づく投資家の損害は、不実表示と投資家の損害との間に、投資家による投資決定という要因が入り込むため、因果関係を、取引因果関係、損害因果関係に分けて分析することは、日本においても有用です。アメリカの判例法の動向は、信頼、損害因果関係、重要性の概念の相互の関係について、一定の示唆を与えてくれるように思われます。
かつて、Fischel 教授は、市場に対する詐欺理論の論理を受け入れれば、公開市場での証券詐欺事件において、重要性、信頼、因果関係及び損害賠償
額を別々に審査する必要はなくなり、不実表示が市場価格に人為的な影響を与えたかどうかのみが問題となると主張しました（Daniel R. Fischel, Use ofModern Finance Theory in Securities Fraud Cases Involving Actively
Traded Securities, 38 Bus. Law. 1, 13（1982））。つまり、因果関係を構成する全ての要件が価格影響性に収れんするという主張です。この議論は、市場の効率性を前提としたものでした。
今日、Halliburton Ⅱ判決が出て、信頼の推定を行うには、市場は効率的である必要はなく、不実表示の価格影響性があれば足りるということが判例・
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学説の共通理解となりました。このように、信頼の推定を行う前提条件を市場の効率性から価格影響性へと緩めた、あるいは変更した場合に、価格影響性があれば不実表示は重要で、不実表示と損害との間に因果関係が認められ、損害賠償額は価格に対する影響の幅によって決定されると言ってよいでしょうか。それとも、Bebchuk & Ferrell の指摘するように、重要性、信頼、因果関係は本来異なる概念であり、市場が効率的である場合にもそれぞれの要件は別個に判断されなければならないのでしょうか。こういった問題を検討することが重要になるように思います。
直観的には、価格影響性があれば、不実表示の重要性、信頼の要件、損害因果関係を認めてよいが、市場が効率的でない限り、価格に対する影響の幅が直ちに損害賠償額になるとは言えないように思われます。
検討の点は甚だ不十分ですが、報告は以上です。よろしくご教示をお願い
します。

討

議

前田副会長

黒沼先生、貴重なご報告をいただき、どうもありがとうございました。
それでは、ただいまの黒沼先生のご報告につきまして、いつもどおり、どこからでも結構でございますので、ご質問、ご意見をよろしくお願いいたし
ます。
中東委員

大変興味深いお話、ありがとうございました。

ご解説いただいた「信頼の推定」とともに、最後に私見としておっしゃった点にも関係すると思うのですが、「効率性」と「不実表示の価格影響性」とは、実態としてどのように使い分けられているのか、教えていただけませんでしょうか。市場が一定程度効率的でなければならないことが価格影響性の問題であるのかとも思えました。つまり、効率的資本市場仮説でいえば、セミストロング型ではあってほしい。そうでなければ価格影響性はない。ただ、ストロング型になってしまうと、そもそも因果関係がなくなってしまう
25

ので、そういう形であってはいけない。ではウイーク型でいいかというと、ウイーク型になると価格影響性がなくなってしまう。こういう話とも理解できるのかなと拝聴しました。もしそうならば、取引因果関係と損害因果関係を分けるというのは、まさにそこに意味があるのかなと理解しました。
黒沼委員

この判決が言おうとしているところは、市場が一般的に効率的であるということを証明すれば信頼は推定されるけれども、個別に当該不実表
示が市場価格に影響を与えなかったということを被告の側で反証した場合には、その推定が覆されるということです。そこで扱われているのはセミスト
ロング型の効率性の概念だけれども、効率性があるかないかが最後まで争点になるのではなく、一般的に効率的であることを証明するのと、それに対して個別に反応しなかったかどうかを問題にする、そういう関係になると思い
ます。
中東委員

よくわかりました。その意味では、信頼性の推定法理が改訂されるべきであるという Bebchuk 教授らの見解のご説明のところで、「効率的な」という言葉を取って全ての情報を反映するのではなく、幾つかの情報を反映するという形に書きかえるのが、先生のご理解を反映したものと考えてよろしいでしょうか。
黒沼委員

私の理解がどうかというより、きょうの報告では余り述べていないのですが、裁判所は Basic 判決を覆さなかったということで、一般的に効率的であるということを今でも前提にしているわけですが、Bebchuk らの議論は、市場が一般的に効率的であることではなく、個別の不実表示が市場価格に影響を与えたことが重要だとしている。彼らは立証責任については、
論理必然的にこうなるはずだとは言えないと言っているので、立証責任は争点になりますが、価格影響性がなければ信頼の推定が覆されるという議論だと思います。
前田副会長

Basic 判決のところで、不実表示と原告の証券購入との間の因果関係が問題になっていますが、不実表示と購入との因果関係と一口に言っても、不実表示がなければより低い価格で買っていただろうという場合と、
26

不実表示がなければそもそも取引がなかっただろうという場合と、２つあると思います。日本でいえば高値取得損害か全部取得損害かという問題です。
きょうの黒沼先生のご報告は、不実表示がなければより低い価格で買っていただろうという意味で分析をなさったという理解でよろしいでしょうか。
少し気になりましたのは、Basic 判決についてご解説、レジメ３ページ「反証の例」の③として「原告は、市場の誠実性を信じたのではなく、他の理由で取引を行った場合」が挙げられていることです。どうせ取引はしていただ
ろうとは言えても、もっと低い価格で買っていただろうと言える場合には、
これは反証にならないように思うのです。十分整理できずに質問させていた
だいているのですが、もっと低い価格で買っていただろうという場合と、そもそも買っていなかっただろうという場合と、きょうの先生のご報告の中での位置づけをご説明いただけるでしょうか。
黒沼委員

御指摘ありがとうございます。アメリカで議論されている Basic

判決における信頼の推定というものはクラス・アクションを前提にした議論なので、前田先生がおっしゃった高値取得損害の場合、虚偽記載がなければ違った価格で取得していたであろうという場合を念頭に置いたものだと思います。Rule 10ｂ‑５は、それ以外に証券会社の従業員による詐欺的な勧誘の場合にも適用がありますが、その場合だと、アメリカでも取得自体損害的な考え方がとられています。そのときには、Basic 型の信頼の推定は認められておらず、その不実表示の影響を受けて取引を行ったことが必要になるという理解だと思います。その点から言うと、Basic 判決が挙げている最後の点の反証、こういう反証を認めるべきなのかどうかというのは議論の余地が大きいと思っております。
市場取引で取得自体損害が認められる場合はどういう場合かというと、私が知る限り、アメリカでもそれほど判例があるわけではなくて、むしろ日本のほうが議論が進んでいるのではないかと思います。上場のための書類に虚偽記載があったために上場されてしまったという事例では、Basic 判決とは違うタイプですが、市場に対する詐欺という概念を用いて取得自体損害の回27

復を認める古い裁判例があります。取得自体損害が市場取引で全く認められないわけではないけれども、少なくともクラス・アクションで問題となるよ
うな場合には高値取得損害を想定している。それを前提にした議論だろうと
思います。
加藤委員

クラス・アクションの認定の段階で、市場における詐欺理論に基づいて原告が立証しなければいけない要件は、Amgen 判決を踏まえると、重要性は落ちることになるという理解でよろしいでしょうか。
黒沼委員

Amgen 判決を踏まえると、落ちているということです。

加藤委員

効率的な市場で取引されているということは言わなければいけな

いけれども、先ほど中東先生との質疑応答であったとおり、被告側が不実表
示は株価に影響を与えなかったということを反証した場合には信頼の推定は得られなくなるという理解ですから、つまり重要性に関する要件が落ちたけ
れども、Halliburton Ⅱは復活したという理解になるのでしょうか。
黒沼委員

そこはアメリカの判例法理の複雑怪奇なところです。Halliburton

Ⅱが Halliburton Ｉを実質的に覆したということは Coﬀee 教授も言っているのですが、Amgen を覆したとは言っていないのです。そこをどう理解するかというのはなかなか難しい。
加藤委員

つまり、Coﬀee 教授や Fox 教授が損害因果関係と価格影響性というのは事実上同じだと言っているけれども、重要性は別の要件である。彼らの理解はそういうことでよろしいですか。
黒沼委員

彼らの理解はそうは明言していないのですが、Bebchuk らはそのように言っています。その違いを、取引時に価格をつり上げたかどうかというのが重要性の問題で、損害因果関係のほうは、発覚時に株価が下落したかどうかという問題だという捉え方をしているのです。その捉え方自身、Dura 判決という判例法理がとった考え方で、それまでは取引時に価格をつり上げたことが重要性であり、かつ損害であると考えられていました。だから、Bebchuk らが言っていることが理論的に正しいのかどうかというのはよくわかりません。
28

中村委員

判決を契機にした Bebchuk たちの考え方をもうちょっとよく理解したいということで、レジュメ 11 ページの「信頼の推定法理は次のように改訂されるべきである」というところについて質問です。（１）は、判決の言っている「穏健な前提」と同じなので特に問題ないと思います。（２）は、単に彼らの考えを言っているだけです。そうすると、実際に裁判でどうこの法理が使えるかというところは、（３）だけに意味があるのではないかと受けとめました。証券の市場が詐欺的にゆがめられていないということが要件になっていますが、ささいなところでは、「証券の市場」なのですか、それとも「証券の価格」が詐欺的にゆがめられていないときですか。市場と価格をどう考えるべきかという点が、１つ、規範として気になりました。
もう１つは、詐欺的にゆがめられていないときというのは一体何なのか。
価格影響性と詐欺的歪曲がほぼイコールということをレジュメの「（3）判旨の検討」の下にお書きいただいています。レジュメの 13 ページの真ん中あたりの Bebchuk のところで、「価格影響性は、損害因果関係の必要条件であるが十分条件ではない」とされています。これも納得はできるのですが、では詐欺的にゆがめられていないときというのは何を立証すればいいのか。価格影響性だけでなくプラスアルファとは何なのかという点で、裁判規範としては使えないおそれがあります。価格ないし市場がゆがめられているというのは何を立証すればよいのか、Bebchuk がどう考えているのかということについて、もしご見解があればご教示いただきたいと思います。
黒沼委員

読み返してみないとわからないのですが、詳しくは述べられていません。信頼の推定法理が改訂されるべきであるというのは、彼らがこれを余り変更しないで使えるということを示すためにこういうことを述べているのであって、彼らの主張の内容からすると、証券の市場が詐欺的にゆがめられていないというのは、市場が一般的に不実表示によって影響を受けないとかそういうことではなく、個別の証券の価格が個別の不実表示によって変動を受けていないということを意味しているのではないかと思います。先生が明確でないと言うのはそのとおりで、このように書くと、一般的な市場の性29質のことを言っているように見えますが、彼らの論旨からすると個別の当該
不実表示の影響のことを言っているはずです。
中村委員

詐欺的にゆがめられていないというのは、重要事項非開示の場合と不実の開示と両方ありますが、それと価格への影響というのはわかります
が、それにプラスアルファが必要ですか。
黒沼委員

そうは考えていないと思います。２と同じです。不実表示がなかったとしても価格は異ならなかったということと同じだと思います。これは不開示の場合にも当てはまるので、不開示の場合には開示があった場合の価格と同じであったであろうということを証明すれば、詐欺的な歪曲はなかったということになります。
中村委員

レジュメの 13 ページで、Dura 判決は価格のつり上げだけでは経済損失の近因にはならなくて、「価格影響性は、損害因果関係の必要条件であるが十分条件ではない」と言ってはいるものの、不実の開示等が価格に影響しない場合があり得ることをもってのみ十分条件ではないと言っていることになるのですか。
黒沼委員

いや、価格に影響したというだけでは十分条件ではない。取引時の価格をつり上げたというだけでは十分条件ではない。Dura 判決はそう言っているので、それを繰り返しています。
中村委員

そうすると、不実の開示と、それによって価格が変動したという事実のほかに……。
黒沼委員

例えば、不実表示によって市場価格が現に上がったとしても、それが不実であることが開示されたときに下がらなかったら損害がないというのか、損害の立証としては不十分だというのが Dura 判決の考え方です。
加藤委員

記憶が曖昧なのですが、Dura 判決というのはかなり特殊な事案だと思います。Dura 判決は、たしか製薬会社の不実表示です。２つの連続してなされた不実表示が問題になっていまして、第１不実表示と第２不実表示と呼ぶことにしますが、Dura 判決の最高裁判例で問題になったのは、第２不実表示の影響を受けて買った人による損害賠償請求です。ところが、第30

１不実表示が発覚したときは株価が下がったのですが、その直後に第２不実表示が発覚したとき、株価は下がらなかったのです。
このような特殊な事案であるということを踏まえると、株価が発覚したときに下がらなかったことにどれぐらい意味があるのか。つまり、第１不実表示の発覚のときに第 2 不実表示の分も合わせて下がっていたのかもしれない。第１不実表示の発覚の段階で、第２不実表示分も下がっていたかもしれないけれども、最高裁判決はそういうことは問題にはしていません。中村先生のご懸念は、不実表示がなされたときに価格影響性があると言いつつ、結局損害因果関係が認められない場合が本当にあるのかどうか、逆に価格影響性がないけれども損害因果関係がある場合があるのかどうか。私は、価格影
響性と損害因果関係の関係は、アメリカの判例法理においても、明確に説明されていないのではないかという印象を持っています。
中村委員

そういう整理というよりは、むしろ信頼の要件が満たされたために、ちょっとこだわるようですが、不実の情報の存在と価格の影響性が認められれば、Bebchuk の言う信頼の要件は実は満たされたことになるのではないか。結局、価格影響性が認められれば信頼の要件が認められるけれども、損害因果関係のほうでは、証拠の共通があるために影響はするけれども十分ではない。済みません、問題を解決しました。
永井オブザーバー

クラス・アクションのクラスの認定の申立て段階で、被告側が事実上の本案審理の一部を争えるようになったというのは、今までクラス・アクションが余りに容易に認められてきたことが改められるという意
味で、この決定を歓迎したいと思います。私的証券訴訟改革法でも、クラス・
アクションの利用は行き過ぎているとされ、制限的に運営される方向にあるので、これをさらに実質的に推し進めるものとして、私はこの部分を評価したいと思います。黒沼先生はどのようにお考えになられてここで評釈されているのか、お伺いしておきたいと思いました。
黒沼委員

私はどちら側ということもありませんが、クラス・アクションという制度に付随するいろいろな問題を考えなければいけないので、これはい
31

ずれ立証しなければいけないけれども、どの段階でどちらが責任を負って立証するかという問題なのです。クラス・アクションとの関係で問題になる。
幾つかの考慮要素があります。
きょうの報告で言わなかったけれども、一つ言われていることは、クラス
認可の前か後かによって、裁判官が判断するのか陪審員が判断するのかが違ってくる。被告は特に裁判官に判断してもらいたいという意向があるから、できるだけ認可前を望む。motion to dismiss とクラスの認可と略式裁判の申立ての順番がどうなっているのかよくわからなかったのですが、レジュメに書いてあるように、恐らく motion to dismiss が最初で、次にクラスの認可、次に正式審理に入ったけれども略式判決の申立てという順番になるのではな
いかと思います。
従来は、認可前に訴答の段階で十分に請求が述べられていないということ
で、motion to dismiss が申立てられて、そこでだめだともう和解してしまうという例もあったのですが、クラス認可のところで争えるようになったというのは被告にとっていいことですし、私も濫訴を防止するためには望ましいことだろうと思います。ただ、そのために、この部分がミニ・トライアル
化するとかディスカバリーが行われるということも言われていますので、正式審理のディスカバリーとは違うとは思いますが、訴訟のあり方としてそれがいいのかどうかというのは、また別個の問題なのかもしれません。
飯田委員

15 ページの上の、先生が説得的だろうかとおっしゃった「鉱山設例」です。Bebchuk 教授たちの考えでいくと、株価が 10％上昇した時点
でクラスワイドな信頼というか、価格が動いたから信頼の要件は認められる
けれども、「金鉱はとても良いと思う」という情報が投資判断に影響を与えるかどうかということは、なお詰めて考える余地のある話だということで、別の重要性の要件で重要性がないと判断する余地もあるという議論をしているように思えます。そうだとすれば、説得力があると言ってもいいのかなと思いました。先生が説得的ではないのではないかとおっしゃった趣旨をもう少し敷衍していただければと思います。
32

黒沼委員

この情報によって株価が動いたならば、それは重要性を認めてもいいんじゃないですか。この設例では、虚偽発言であることを証明したと言っているのです。ですから、「とても良いと思う」というのは虚偽表示とは言
わないというのであれば話は別ですが、それが不実表示であるならば、直ちに重要性が認められてもいいように思います。ここに書いてあるようなことを判断しないと重要性の要件は認めるべきではないということですかね。
飯田委員

レジュメに「なぜなら」と書いてあるようなことを？

黒沼委員

そうです。

飯田委員

確かに、ここに書いてある「なぜなら」以下の事実の争点が重要性の要件で今まで語られてきたものとは違うものであるように私も思いますが、概念として別であるという話とか、会話をして「金鉱はとても良いと思う」という発言を市場がニュースとして受けとめて株価が勝手に上がった。
ニュースに反応したにすぎないのであって、不合理な株価の動きにすぎな
かったという議論は、可能性はあるのではないかと思ったのですが。
黒沼委員

それは価格影響性でもないということですか。

飯田委員

価格影響性とは違うものではないかと思います。

黒沼委員

他の要因で上がったのであれば、価格影響性はなかったということになるような感じがするのですが。
飯田委員

この発言をしたこと自体で株価が上がっているということは、価格影響性の要件を満たすものであるということです。重要性というのはもう少し規範的に評価するものではないかと思いました。
黒沼委員

ちょっと考えてみます。

中東委員

私も、飯田先生と同じように思いました。CEO が「金鉱はとてもよいと思う」と発言したとしても、金鉱から金を掘り出す費用等も考えて、事業ベースに乗るかどうかという話とはまた別の問題である可能性があると思います。ですので、CEO が「金鉱はとても良いと思う」と言ったことに規範的な問題として重要性があるかというと、ほかに何を発言したかなども考えなければならないと思います。
33

加藤委員

私は、黒沼先生と同じような疑問を抱きました。確かに、CEOの発言によって株価が 10％動いたということを規範的に評価することが重要性の問題であると思いますが、株価が動いた理由は、一応「金鉱はとても良いと思う」という情報の内容と、恐らく会社の CEO（社長）が発言したということ自体の影響も含まれていると思います。そう考えた場合、例えば重要性というものをある程度熟した情報についての不実開示だけと捉える考
え方も間違いではないかなという気もしますが、やはり社長の発言はミスリーディングであってはいけないということで、社長の発言によって株価が過度に動いた以上、重要性はあるという結論もあり得るのではないかと考え
ました。
飯田委員

最初の中東先生との応答の中で黒沼先生がセミストロングフォー

ムの効率性は必要なのではないかとおっしゃったところに関して、もしかしたら私の誤解かもしれないのですが、Halliburton Ⅱはセミストロングである必要もないと言ったのではないかと思いましたが、そういう理解でよろしいでしょうか。
黒沼委員

私は、ここで問題とされている市場の効率性はセミストロングの話であると思います。Halliburton 判決自身は価格影響性について当事者がクラス認可の段階で争ってよいと言っているのですが、Basic を変更しなかったということからすると、市場の効率性とその他のことを言えば推定される、価格影響性の間接的な証明になるという線は維持しているので、市場の一般的な効率性を主張、立証すればいいというのは、これからも続いていく話ではないかと言ったのです。
飯田委員

その一般的な効率性というのが必ずしも理解しにくいのです。何かグッドニュースがあって少し株価が上がったとかではなくて、適切な水準
で株価が即座に上がるということまで要求するような概念であれば、セミス
トロングの効率性を要求しているということとイコールだと思いますが、そこまで言っているのでしょうか。
黒沼委員

一般的な効率性というのは、ここではニューヨーク証券取引所の34

市場は効率的である、ニューヨーク証券取引所で取引をしている株式である、
そういうことを言っているのにほぼ等しいと言われています。具体的には、先ほど紹介したような５要素などを見ているようですが、その点については
本当の意味の効率性とは違うのではないかという批判はあると聞いています。ただ、実務では、効率性が認められなかったという例はほとんど聞かな
いので、そういう場合には、クラス認可はほぼ自動的に与えられてきたと言
われています。
中村委員

今の点に関連して質問が１点と、追加で１点です。

１点目は、例えば日本の Jasdaq 証券市場に置きかえてみた場合、いつも値がついている株式といつも値がつかない株式があっても、Jasdaq 証券市
場で取引されているというだけで一般的な効率性が認められることになるのでしょうか。
２点目は、クラスワイドの信頼の要件と個別の投資家の信頼の要件を分けて考えることができる。これを日本に置きかえた場合、例えばレジュメの中にもお書きいただいていましたが、ポートフォリオのリバランスのために取引する場合とか、高速取引をする場合とか、不実の情報と関係ない動機で売買される場合において、相当因果関係を取引因果関係と損害因果関係に分けて分析するかどうかにもかかわってくると思いますが、相当因果関係が認められないという結論に結びつき得るものかどうか。これについてお考えがあればお聞かせください。
黒沼委員

私は、以前から Basic 判決は効率的資本市場仮説を実質的には採用したものだと考えてきましたし、効率的な市場ではどういう法理が成り立つかを研究してきたのですが、改めて考えてみると、このような因果関係が認められるためには、市場は効率的である必要は必ずしもないというのはそのとおりだと感じます。
Jasdaq の効率性は仮定の話になりますが、効率性という概念を用いて、だから損害賠償額がこうなるでしょうというときには、当該有価証券について効率的な市場が成立していたということが前提になるので、どちらが立証
35

責任を負うかということが問題だけれども、一般的な取引所のそのセクションの効率性といったものでは本来は足りない話だと思います。
日本の場合に置きかえて一般的に因果関係の問題を考えていくときには、
日本の条文には信頼の要件はありませんが、不実表示が取引を引き起こしたという関係は別に必要ではなくて、先ほど前田先生が言われたように、不実
表示がなければ異なった価格で取引をしたであろうという主張をしている限
りは、不実表示が価格に影響を与えて、当該価格で取引をしたということのみが問題なわけです。他の理由で取引をしたということは、因果関係の反証にはならないのではないかと個人的には思います。
中村委員

１点目は同感で、２点目についてはまた勉強してみたいと思いま

す。
前田副会長

大きな質問になってしまって恐縮ですが、日本の場合、不実表示があって、一般不法行為責任が追及されるような事例であれば、信頼の問
題とか、相当因果関係を詰めて問題にしなければならないのでしょうけれども、現在の金商法に基づく会社の責任とか役員等の責任については、損害賠償額が法定され因果関係の立証も不要とされ、あるいは損害額とか因果関係の推定規定が置かれるという形で、きょう先生がご報告くださったアメリカの判例法に比べると、きめ細かな議論が余りされていないように思います。
立法論として考えた場合、アメリカの法制と比べて、日本の現在の金商法の虚偽記載があった場合の責任規定は、どう評価したらいいのでしょうか。
黒沼委員

大変難しい問題で、実際には極めて重要な問題だと思います。日本の場合には、かつては判例もなかったわけですが、21 条の２ができてから、判例もふえてきました。ただ、21 条の２は推定規定になっているので、因果関係の反証ということが問題になって、その限りで幾つかの判例法理が出てきています。
しかし、これがあるために、例えば取締役の責任と会社の責任を同時に追及しているときに、発行者の責任については 21 条の２が適用されて、取締役については 24 条の４になるので、立証責任も違うし、推定額もあるかな
36

いかの違いがある。しかし、事実は１つの事実で、そこから生じた因果関係のある損害とは何かということが問題になっているのは同じなのに、そこで違った結論が出てくる。推定規定で裁判所が因果関係の反証を認めずに判決を出してしまったら、それは 24 条の４の訴訟でも全く同じ額を使うことになるのかとか、そのあたりの裁判例がどうなるのか、よくわからないところです。裁判例が積み重なって判例法理が出てくれば、日本は理論的にも非常におもしろい状況になるだろうと思っています。
アメリカと日本のどちらがいいのかという点については、推定規定を置いたために、ちょっとアンバランスなことが起こっている。ほかの条文にも推定規定を置いてほしいと言ったのですが、それは実現しなかったのです。その点ではやや変則的だけれども、訴訟で争われて、最後までいって判決が書かれる例は、実は日本のほうが多いわけです。そういう意味では、実際に賠償が命じられる損害額は何かということを真剣に議論する場が日本では置かれています。そういう意味では、日本はいい状況ではないかと思います。
アメリカでは、因果関係の訴答段階とか略式裁判の段階で専門家の鑑定が出てくることはありますが、判決がそれに依拠して損害額を算定するという裁判はほとんどなくて、最後に陪審にいってしまうと判例集に載らないのです。因果関係、損害賠償額についての判例法理がきちんと裁判にあらわれるという点では、日本は恵まれているというか、いい状況ではないかと思います。
飯田委員

日本の 21 条の２の２項の損害の推定等を考えるに際して、市場は効率的であるということが前提となっていると考えるべきなのかということについて、最終的には被告側で因果関係がないことを立証すればいいとい
うことなのでしょうけれども、その辺について黒沼先生のご意見があれば教えていただきたいと思います。
黒沼委員

今回のアメリカの判例を改めて勉強し直してみて、確かに学説は以前から市場の効率性ということは言わなくてもいいと指摘していたようで、言われてみればそのとおりだなと思うところはあります。そういう意味
37

では、不実表示が市場価格に影響を与えている限りは、そういう推定規定を置くことに合理性はあると思いますので、市場が効率的でないような場合であっても、不実表示が価格に影響を与えたという要件が満たされれば、推定規定を及ぼす基礎はあると思います。
そこから先は考え方の違いといいますか、推定規定が取得時差額を念頭に置いてそれを算定するための規定なのか、それとも市場下落が損害であって、それを算定するための式なのかによっても考え方はさらに違ってくるのです
かね。市場下落が損害だということになると、それは市場が効率的であってもなくてもそれだけの損害をこうむったと考えるということになれば、推定規定そのままということになります。取得時差額の場合は、取得時差額がそのまま移っているという考え方に基づいていますから、反証の仕方が少し違ってくるのかもしれません。
ただ、ライブドア事件判決によると、推定規定を設けるときの反証といいますか、損害額の減額の判断においても、ろうばい売りによる損害も含むという考え方をとっています。そういう考え方をとる以上、仮に市場が効率的ではないということを被告の側で証明したとしても、それは反証にはならな
いのではないかと思います。
飯田委員

そうすると、市場の効率性が前提となっているという議論ではな

い方向に判例法理は向かっている、というご理解と伺いました。ありがとうございました。
黒沼委員

飯田先生のお考えをお聞かせいただければ。

飯田委員

それはまた別の機会にさせていただければと思います。

神作委員

黒沼先生からご紹介・分析をいただいた判例や学説が、アメリカ

証券法の他の領域や全体に与える影響の有無についてご質問させていただきます。
アメリカの証券規制の考え方は、市場の効率性に関する理論を前提にしていると思います。不実開示による損害賠償といった本日取り扱われた論点だ
けでなく、たとえば内部者取引規制や、そもそも強制的なディスクロージャー
38

制度のあり方など、いろいろなところで市場の効率性に関する理論を前提にした規律があると思います。そういう意味で、ご紹介いただいたアメリカの判例法理が首の皮一枚か二枚かわかりませんが、市場の効率性および市場に対する信頼の推定を維持しているのは、何とかそれによって、アメリカ証券規制が理論的な前提にしてきたと思われる市場の効率性を通じた投資者保護のあり方に関する従来の議論との接続を図ったためであるような気もします。しかし、実質的には、一連の判例は、これまでのアメリカの証券法を支える基本的な理念の部分を相当切り崩しているような印象も受けます。不実開示に係るこれら一連の判例が、証券法のほかの分野あるいはアメリカの証
券規制全体に対して及ぼすインパクトについて、アメリカでは一体どのように受けとめられているのかについて、ご感触を伺えればと思います。
黒沼委員

私が当たった資料では、残念ながらそういうことを論じているものはありませんでした。せいぜいクラス・アクションの件数がふえるか減る
かとか、保険会社の支払いがふえるか減るかとか、この判決でそれぞれの裁判官が証券訴訟に対してどういう見方をしているかとか、誰がどうなるかとか、そういう実務的な関心が多かったです。
しかし、もともとこの分野は判例法が規律している分野で、95 年の改革
法が、一部訴答要件を厳格化したりして、損害賠償請求をやりにくくしました。ただ、アメリカ全体の判例法や制定法の動きを大ざっぱに言うと、時代によって波があります。クラス・アクションの弊害が強く言われたので 95
年に改革したけれども、そのことが遠因になって、エンロンとかワールドコ
ムの事件が起きたと言われます。サーベンス・オックスレー法では、証券法がコーポレート・ガバナンスにも介入するような規制の強化を生みました。
ですから、行ったり来たりしているというのが実情ではないかと思います。
これを機会に判例がどういう方向に進むかという点も、判例変更はしなかったけれども、一部発行者に有利な争う手段を広げるような判示をしたという意味で、実質的にどちらが喜んでいるかということも見解は分かれているようです。
39

お答えにならなくて申しわけないのですが。
永井オブザーバー

先ほど飯田先生もおっしゃいましたが、市場の効率性というのはすべからくの上場株式に対して言えるものでは当然なくて、株式の発行数とか時価総額の大きさとか、影響の及ぶ範囲がそれぞれ違う。ですから、先ほど中村先生がおっしゃったように、Jasdaq とか取引規模が小さい
会社に関しては、その前提はもともと余り議論されておらず、市場の効率性は余り働かないことを前提に、もともと議論されているのではないか。そうすると、市場の効率性をあくまでも前提としなければならない、と言われると、私はそのようには思わず、それの与える影響度合いがどの程度の人に広く影響していくかということのほうが、むしろ重要ではないかと思います。
その点、感想めいた話で申しわけないのですが、いかがでしょうか。
黒沼委員

そのとおりだと思います。それと関係するかどうかわからないのですが、例えば、アメリカでは５要素テストがあって、Ｓ‑３の対象になっているかどうか。これは、日本でいうと参照方式です。そのような要件が挙がっているわけです。アメリカでは、参照方式を導入するときに、各銘柄の市場の効率性についての実証研究をしています。ところが、日本で参照方式
や組込方式を入れたときには、それはやっていないわけです。しかも、その後の規制緩和で参照方式の適用範囲を広げたりしています。むしろ、市場の効率性は、そういう制度設計のほうに影響を及ぼすべき話というか、きちんと考慮してやるべき話であって、お答えにはならないのですが、そういう意
味で重視していく面があるかもしれません。
前田副会長

まだ若干時間がございますが、ほかはいかがでしょうか。特になければ、これで質疑応答を終わらせていただきます。黒沼先生、どうもありがとうございました。
それでは、今後の研究会のアナウンスをさせていただきます。第５回会合
は、平成 27 年の１月 28 日、午後２時から、飯田秀総先生がご報告くださり、
第６回会合は、平成 27 年３月 23 日、午後２時から、山田剛志先生がご報告
くださることになっています。
40

それでは、本日の研究会はこれで閉会とさせていただきます。どうもありがとうございました。

41

［報告者レジュメ］
市場に対する詐欺に関する米国判例の動向について
黒沼 悦郎
１ はじめに２ 34 年法規則 10b-5 の要件
1934 年証券取引所法（Exchange Act of 1933）10 条(b)項、34 年法規則 10b-5
詐欺防止条項（anti-fraud provision） 総称して Rule10b-5 という。
黙示の私的訴訟原因（implied private cause of action）
要件(1) 被告による重要な不実表示または省略(2) 欺罔の意図（scienter）(3) 不実表示または省略と証券の売買との関係（in connection with）(4) 不実表示または省略への信頼（reliance）(5) 経済的損失（economic loss）(6) 損害因果関係（loss causation）
信頼の要件
特定の原告が投資判断を行うにあたり、不実表示を重要な要素と考えたこと
省略（不開示）：開示されなかった事実を知らされていたら原告が異なった行動をするような影響を受けたであろうこと
取引因果関係（transaction causation）とも呼ばれる。
３ Basic 判決（1988 年）1【事実】Basic 事件では、Basic 社が合併の交渉中であるという事実を隠し、合併交渉をしていな
いとの声明を発表したことに対し、Basic 社株を売却した株主が会社および取締役の責任を追及するクラス・アクションを提起した。
連邦民事規則 23 条(b)項(3)号によると、個々の原告に関する個別の問題よりも、クラスに共通の法律問題または事実問題が支配的で（predominate）なければ、クラスの認可（certification）は認められないところ、連邦地方裁判所は、信頼の推定を認めクラスを認可した。第 7 巡回区控訴裁判所はクラスの認可を維持したので、最高裁は、合併交渉に適用される重要性の基準（がいかにあるべきか）とともに、クラスの認定の際に、裁判所が、
Basic Inc., v. Levinson, 485 U. S. 224 (1988). 解説として、拙稿「会社情報の開示と民事責任－Basic 判決を中心として―」名古屋大学法政論集 133 号（1990）1 頁。
1

１

1
42

表示に対する直接的な信頼をクラス・メンバーに要求せず、信頼の推定を及ぼしたことが適切かどうかについて裁量上訴を認めた。
【判旨】
法廷意見
市場に対する詐欺理論（fraud on the market theory）とは、公開市場において会社の株
価は、会社およびその事業に関する情報に基づいて決定されているとの前提に立ち、原告が不実表示に直接依拠しなかった場合でも、被告の不実開示と原告の証券購入との間の因果関係を認める理論である。我々の仕事は、市場に対する詐欺理論の有効性を一般的に評価することではなく、裁判所が、部分的に市場に対する詐欺理論に依拠して、信頼の反証可能な推定を認めたことが適当かどうかを考察することにある。
原告に、開示されなかった事実が開示されたとしたら、あるいは、不実表示がなかったとしたら、どのように行動していたかを立証させることは、公開市場で取引をした原告に、不必要かつ非現実的な立証責任を課すことになる。信頼の推定は、公正、公序、蓋然性、および訴訟経済の観点から見ても、当事者間で立証責任を分配する有用な方法である。本
件で採用された信頼の推定は、Rule10b-5 訴訟を促進することになるが、それは、証券市場の誠実性（integrity）に対する投資者の信頼を促進するという 1934 年法の立法政策とも整合的である。
推定は、コモンセンスおよび蓋然性からも支えられている。最近の実証研究は、高度に発達した市場で取引される株式の市場価格が、すべての公開情報を反映しており、したがって、重要な不実表示をも反映していることを示している。
・・市場で形成された価格で株式を売買する投資者は、当該価格の誠実性を信頼して売買を行っている。多くの（most）
公開情報は市場価格に反映されているから、公開された重要な不実表示に対する投資者の信頼は、Rule10b-5 訴訟の関係において、推定されうるのである。
White 判事、O’Connor 判事の反対意見の要旨
経済理論を法原則に取り入れるとしても、それは、裁判所よりも専門家の助けを得ることのできる議会が、法律改正によって行うべきである。
投資者が「株価をその株式の価値を反映するものとして信頼していること」は疑問である。多くの投資者は、株価が会社の価値を反映していないと信じるからこそ株式の売買を行うのではないか。
市場に対する詐欺理論は、34 年法 18 条(a)項が要求する厳格な信頼の要件を骨抜きにする点、および情報をみない投資者を保護する点で、34 年法の立法目的に反している。
【解説】
Basic 判決は、当該事件の控訴裁判所が採用した「推定」を適切であるとしたが、控訴審
２2
43

では、推定が認められるためには、原告は、(1) 被告の不実表示が公表されていること、(2) 不実表示が重要であること(3) 株式が効率的な市場で取引されていること(4) 不実表示が、投資家に株式の価値を誤って評価させるものであること(5) 原告が、不実表示がなされてから真実が発覚するまでの間に株式の取引を行ったことを主張し、証明しなければならないとする。ただし、(4)は後の判例では要件から除外されている。
不実表示と原告の受け取った（または支払った）価格との間の繋がり、または不実表示と市場価格で取引を行うという原告の決定との間の繋がりを断ち切るいかなる証明も、信頼の推定を覆す。
（反証の例）①

マーケット・メーカーが真実を知っており、市場価格が不実表示の影響を受けなかった場合② 真実の情報が市場に到達しており、不実表示の影響を打ち消していた場合③ 原告は、市場の誠実性を信じたのではなく、他の理由で取引を行った場合
４ HalliburtonⅠ判決（2011 年）2【事実】
EPJ Fund が、Halliburton 社が、(1)アスベスト訴訟の潜在的な責任の範囲、(2)ある建設契約から生じる予想収益、および(3)他の会社との合併の便益について、故意に、さまざ
まな虚偽の開示を行ったと主張して、1999 年 6 月 3 日から 2001 年 12 月 7 日までに H 社の株式を購入した者を代表してクラス・アクションを提起した。
却下の申立て（motion to dismiss）を退けたのち、地方裁判所は、EPJ Fund は、請求に係る損害因果関係を証明しておらず、連邦民事規則 23 条(b)項(3)号の要件を充たさないとして、クラスの認可を拒絶した。第 5 巡回区の先例は、クラス認可を得るために原告に損害因果関係の立証を求めていた。
クラス認可のために損害因果関係の立証が必要かどうか、巡回区の不一致を解消するた
めに、最高裁は裁量上訴を認めた。
【判旨】 破棄差戻し
本件下級審は、クラス認可における共通性の要件を充たすために、信頼の立証が必要でErica P. John Fund, Inc. v. Halliburton Co., 131 S. Ct. 2179 (2011). 解説として、藤林大地「市場における詐欺理論の適用と損害因果関係の立証の要否」商事 1979 号（2012）53
頁。
2

３

3
44

あり、信頼の証明のためには損害因果関係の証明が必要と考えた。
しかし、控訴裁判所の要件は、Basic 判決の論理からは正当化されない。損害因果関係は、投資家が不実表示を信頼したか否かとは関係のない事柄に関するものである。後の損失が不実表示の発覚以外の要因によって生じたという事実は、投資家が最初の段階で不実表示を信頼したかどうか（それが直接であれ、推定される場合であれ）とは関係がない。
Halliburton は、本件下級審が損害因果関係の名の下で実際に問うたのは、主張された不実表示が最初の段階で市場価格に影響を与えたか、すなわち価格影響性（price impact）の有無であったと主張する。しかし、控訴裁判所が言おうとしたとことを Halliburton がどう考えるにせよ、実際に言ったのは損害因果関係である。
５ Amgen 判決（2013 年）3【事実】
コネチカット退職年金ファンドが、バイオテック会社 Amgen とその役員（併せて Amegenという）に対し、証券クラス・アクションを提起し、信頼の要件については「市場に対する詐欺」推定を援用し、クラス・アクションの認可を求めた。地裁はクラスを認可し、第 9巡回区控訴裁判所は、退職ファンドはクラス認可の前に虚偽記載または省略の重要性を証明する必要があるとの Amgen の主張を退け、クラスの認可を維持した。同裁判所は、また、クラス認可の段階で Amgen が提出した、重要性の反証となる証拠を考慮することを地裁が拒絶した点に誤りはなかったと判示した。最高裁は、クラス認可のために重要性を立証する必要があるかどうかについて、巡回区の不一致を解消するために、裁量上訴を認めた。
【判旨】
重要な問題は、クラスに共通する法または事実の問題が、個々のメンバーのみに影響する問題に対して支配的であるといえるためには、重要性の証明が必要かどうかである。その答えは 2 つの理由により「否」である。
第 1 に、重要性は客観的な基準に従って判断できるので、クラスに共通の証拠によって証明され得るからである。したがって、重要性は、23 条(b)項(3)号にいう「共通の問題」（common question）である。
第 2 に、原告が略式判決の申立てや本案において、重要性の十分な証拠を提出できなかったときは、個々人の信頼の問題がクラスに共通の問題に優越するという事態を招くことはない。重要性の要件の証明に失敗したときには、すべての者にとって訴訟は終了し、個々人の信頼という争点が支配的になるような請求が残ることはない。

3 Amgen Inc. v. Connecticut Retirement Plans and Trust Funds, 133 S. Ct. 1184 (2013).
解説として、藤林大地「証券集団訴訟の認可と不実表示の重要性の立証の要否」商事 2015号（2013）38 頁。

４

4
45

Amgen は、市場に対する詐欺理論の前提条件はクラス認可の前に充たされなければならないから、前提条件の一つである重要性もクラス認可の前に証明されなければならないという。しかし、重要性と異なり、市場の効率性および不実表示が公表されたことは、
Rule10b-5 の欠くことのできない要素ではない。後２者が証明されなくても、信頼の個別的立証が許されるが、重要性が証明されなければクラスの請求全部が棄却される。市場の効率性や公表の争点と異なり、重要性の争点が証明できなければ、個別問題が共通問題に優越することはないので、重要性は 23 条(b)項(3)号のクラス認可の前に証明される必要はな
い。
Amgen は、クラス認可は和解への大きな圧力となるから、認可前に重要性を争えないと、重要性を争う場面がなくなると主張する。しかし、その点は、不実表示や損害因果関係の要件についても同じである。議会は和解の圧力に対して、クラス認可段階で重要性の証明を求めること以外の手段によって対処したのであり、これに加えて裁判所が 23 条(b)項(3)号の再解釈により調整を行う必要はない。
Amgen は、原告の申立てに対して、重要性の反証を提出できないとした点に地裁判決の誤りがあると主張する。しかし、主張された不実表示が最終的に重要でないとされる可能性があることは、共通問題が支配的であることを妨げるものではない。本件の地方裁判所
が、Amgen の反証の考慮を略式判決または事実審（トライアル）にとっておいたのは正しい。
本判決では、Thomas 判事が反対意見を記載し、Kennedy 判事がこれに同調、Scalia 判
示もその一部に同調している。
【解説】
不実表示の重要性は、市場に対する詐欺理論による信頼の推定を認める要件の一つなのに、クラス認可の段階で証明を要しないのはなぜか。
← 重要性が客観的証拠によって証明できるという点で「共通の問題」である。
仮に本案において重要性が証明されなかった場合には、訴訟は終了するので、改めてクラスの認可を判断する必要がない。
クラス認可の段階で重要性の証明が不要→被告は重要性を反証する証拠を提出できない

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６ HalliburtonⅡ判決4【事実】
HalliburtonⅠの差戻審において、被告は、損害因果関係の反証として提出していた証拠
は、不実表示が価格に影響を与えていなかったことの証拠でもあると主張した。地裁はHalliburton の主張を取り上げることを拒否し、第 5 巡回区控訴裁判所も、価格影響性（priceimpact）の反証は事実審でのみ認められるとした。最高裁は、①Basic 判決の信頼の推定を覆したり、修正したりすべきかどうか、②もし修正しない場合、被告は、クラス認可の段階で、価格影響性の欠如を証明することにより、推定を反証する機会を与えられるべきかどうかの２点について、裁量上訴を認めた。
【判旨】【法廷意見】（Roberts 判事ほか 6 名）
１ 信頼の推定理論の維持
Halliburton は、Basic 判決の２つの前提が今日では成り立たないので、判例が変更されるべきだと主張する。
第 1 に、今日では、効率的資本市場仮説（efficient capital market hypothesis）が成り立たない証拠がいくらでもあるという。たしかに、ある証券についての市場は他の証券についての市場よりもより効率的であり、ある一つの市場も、種類の異なる情報に対しては、より効率的であったり、効率的でなかったりする。
Halliburton は、市場の株価が会社の公開情報を反映する程度に関する経済学者の議論に焦点を当てるが、Basic 判決の裁判所は議論があることは認めており、信頼の推定を認める
ことは、公開情報がどれだけ早く正確に市場価格に反映するかについての特定の理論を採用することを意味するものではないと述べている。裁判所は、一般的にいって、市場のプロが、会社に関する公表された重要な情報、従って市場価格に影響を与えるような情報の多くを（most）を考慮しているという穏健な前提を置いているだけである。Halliburton
が引用する学説は、このような穏健な前提を否定するものではない。
第 2 に、Halliburton は、投資者が市場価格の誠実性（integrity）を信頼して投資を行うという、Basic 判決が仮定に置いている命題を攻撃する。Halliburton は多くの例を引用
するが、そのうち重要なのは、株式が過小評価または過大評価されていると信じている価値投資家（value investor）であろう。しかし、Basic 判決は価値投資家の存在を否定する
ものではない。そのような投資家は、株価が最終的には重要な情報を反映すると暗黙のう
ちに信頼しているのである（そのような市場修正がないとしたら、どうやって価値投資家
は利益を得るのか？）。たしかに、価値投資家は取引の時には価格を信頼していない。しかし、信頼の推定を受けるためには、合理的な期間内に市場が情報を反映すると信じていれ
Halliburton Co. v. Erica P. John Fund, Inc., 134 S. Ct. 2398 (2014). 解説として、池谷誠「Halliburton 事件最高裁判決の検討」商事 2042 号（2014）41 頁。
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ば足りる。
Halliburton およびその賛同者は、Basic 判決は、証券クラス・アクションを促進することにより、深刻で害のある結果を引き起こしてきたと主張する。しかし、そのような心配は議会によって対応されるべきものであり、すでに 1995 年の私的証券訴訟改革法（Private
Securities Litigation Reform Act of 1995）によって対処されてきた。
２ クラス認可段階における反証
Halliburton は、Basic 判決を変更する２つの提案をしている。
第 1 は、信頼の推定を発動させるために、原告は、不実表示の価格影響性を証明しなければならないというものである。たしかに、Basic 判決が採用した信頼推定の４つの要件（公表、重要性、市場の効率性、取引の時期）のうち、前３者は価格影響性に向けられたものである。しかし、Basic 判決の信頼推定の要件は２つの構成要素からなる。第 1 に、原告が、不実表示が公表されており、重要であり、かつ原告が、一般的に効率的な市場で取引をしたことを証明した場合には、彼は不実表示が価格に影響を与えたとの推定を受けることができる。第 2 に、原告が、関連する期間に市場価格で株式を購入したことを証明した場合には、彼は不実表示を信頼して株式を取得したとの推定を受けることができる。原告が価格影響性を直接に証明しなければならないという Halliburton の提案は、第 1 の構成要素を原告から奪うことになる。市場の効率性はあるかないかの命題ではないから、一般的に効率的な市場において、重要な不実表示が株価に影響を与えないこともあり得る。だからこそ、Basic 判決は、特定の不実表示が価格に影響を与えなかったという反論の機会を被告に与えている。我々は、Basic 判決を半分廃棄することになる原告の主張を認めることはできない。
第 2 に、Halliburton は、クラス認可段階で、不実表示が株価に影響を与えなかったという証拠により、推定を覆すことを認めるべきだと提案する。我々はこの提案に賛成する。
従来から、クラス認可の段階で被告が価格影響性を否定する証拠を提出することは、それが、推定の反証ではなく、市場の効率性を反証する目的を持つ限り、認められてきた。
しかし、このような制限は意味がなく、奇妙な結果を招く。たとえば、クラス認可の段階
で、被告が６つのイベントに関するイベント・スタディを提示し、そのうちの１つが被告の不実表示であったとする。地裁が、市場は効率的であったが、不実表示に対しては市場の反応がなかったと認定した場合、これは信頼の推定を覆すものではないという理由でクラスを認可することはおかしい。
このようなおかしな結果は Basic 判決の論理とも矛盾する。Basic 判決の市場に対する詐欺理論の下で、信頼の推定を発動させる市場の効率性と他の前提条件は、価格影響性を間
７748

接的に証明するものである。そうだとすれば、被告には、価格影響性の直接的な反証を認めるべきである。
控訴裁判所は、Amgen 判決に依拠して、Halliburton はクラス認可の段階で価格影響性の反証を提出できないと判断した。しかし、Amgen 判決は、クラス認可の段階で原告が重要性を証明しなければならないかどうかについて判示したものである。重要性は Basic 判
決の推定の前提条件であるが、それは連邦民事規則 23 条(a)項(3)号の支配性の要件と関連しないので、本案まで持ち越されると我々は判示した。EPJ Fund は、価格影響性の要件も重要性の要件と同じであるという。しかし、価格影響性は重要性と重要な点で異なる 。価格影響性は、Basic 判決の基本的な前提であり、クラス認可段階の支配性の争点と深く関係している。
他の要件がクラス認可の段階で証明されているのであれば、クラスに共通する要件である重要性を本案段階に持ち越したとしても、クラスの認可をあとで覆すような事態には至らない。 これに対し、価格影響性については、クラス認可段階ですでに間接的な証拠が提示されているのであり、クラス認可段階で、直接的な証拠による価格影響性の反証を認めない理由はない。
【Ginsburg 判事、Breyer 判事、Sotomayor 判事による賛成意見】
価格影響性の考慮を本案段階からクラス認可段階へ早めることは、認可段階で利用できるディスカバリーの範囲を拡げることになる。もっとも、価格影響性がないことの立証責
任は被告が負うので、本判決は証券訴訟の原告に追加的負担を課すものではない。以上の理解を前提として法廷意見に賛成する。
【Thomas 判事、Scalia 判事、Alito 判事の意見（実質反対意見）】
Basic 判決による信頼の推定は誤りであった。その理由は第 1 に、裁判所が、争いのある経済理論と投資家の行動についての誤った直観に依拠したからであり、第 2 に、それが、クラス認可を求める原告に、個別の争点より共通の争点が支配的であるという要件の立証を求める連邦民事規則 23 条に関する判例法に反するからである。第 3 に、推定された信頼
は、ほとんど反証することが不可能であり、信頼の要件を廃止するのに等しいからである。
Basic 判決が前提とする事実のうち、公表情報が市場価格に反映されているという点は、効率的資本市場仮説に立脚したものであるが、Basic 判決以来、その経済理論は広く批判にさらされている。また、市場が公表情報を反映するにしても、正確に反映するとは限らないことを示す多くの実証研究がある。

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Basic 判決が前提とするもう一つの事実、すなわち投資家は市場の誠実性を信頼しているという点は、誤りである。多くの投資家は、市場が株式を過大評価または過小評価していると信じているからこそ、取引をしているのであるし、他の投資家は、価格と関係のない理由で、たとえば流動性の需要、税金の考慮、ポートフォリオの組換えのために取引している。
多数意見は、穏健な前提を置くことで理論と現実を架橋しようとする。しかし、そのような穏健な前提は、Basic 判決の判決文言と整合しない。また、多数意見は、市場が過大評
価・過小評価している価値投資家も、将来、市場価格が公表情報を反映することを信じているというが、取引の際に市場価格が公表情報を反映していなければ、投資家は、公表情報が彼を取引に誘い込んだと主張することはできないはずである。
Basic 判決は、被告に反証の機会を与えているようにみえる。しかし、クラス認可の段階
では、反証はクラス代表に対してのみ、なされるので、クラス代表の信頼を反証することは難しい。クラス認可後は、裁判所は信頼の要件の反証を拒絶してきた。信頼の反証を認めた事例は、何千もの Rule10b-5 訴訟中 6 件しかないという。Basic 判決は、信頼の要件を実質的に廃棄するのに等しい。
【解説】
１ 信頼の推定（１）効率的資本市場仮説に依拠するものでないこと
Basic 判決が出された 1988 年以降、情報に対する証券市場の効率性については、疑義を呈する実証研究が多数公表されており、市場に対する詐欺理論の基礎が揺らいできた。
多数意見は、市場に対する詐欺理論は、市場の効率性を前提とするものではないとして、
Basic 判決を維持した。Basic 判決が特定の経済理論に依拠しているものでないことは、たしかにその通りである。しかし、「市場の効率性」は、依然として、信頼の推定のための要件の一つとされている。
学説では、Basic 判決は、市場に対する詐欺理論と効率的市場仮説を結びつけたが、本来、ある証券の市場価格が詐欺情報を反映している限り、市場に対する詐欺理論により信頼を推定するために、証券市場が一般的に効率的であることを示す必要がないことが、比較的早くから指摘されてきた5。HalliburtonⅠおよび HalliburtonⅡでは、多くの学者が裁判所の友（amici curiae）として意見を寄せたが、それらの多くも、裁判所は市場が効率的であるかどうかではなく、特定の不実表示が市場価格に影響を与えたかどうかに着目すべきで
Jonathan R. Macey et al., Lessons from Financial Economics: Materiality, Reliance,and Extending the Reach of Basic v. Levinson, 77 Va. L. Rev. 1017, 1021 (1991).

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あるとしている。
（２）Bebchuk & Ferrell の見解6
一般に、市場は、利益を得る裁定機会（arbitrage opportunity）がない場合に効率的であると定義されてきた。
しかし、第 1 に、裁定機会の存在は、詐欺による市場価格の歪曲（fraudulent distortion）の存在を否定するものではない（市場が効率的でなくても、詐欺による市場価格の歪曲は起こり得る）。
市場の効率性は３つの分野で争われてきた。①市場は長期的な収益を過大評価している。
②過剰なボラティリティ。③情報に対する市場の反応の鈍さ。
① 過大評価設例
市場の株価収益率が歴史的に 15 倍であったところ、現在、市場が長期的収益を過大評価
し、20 倍となっていた。企業が収益を 1 ドルのところ 2 ドルと不実表示した。株価は 20ドルから 40 ドルに上昇し、不実表示の発覚により株価は 20 ドルに戻った。その後、市場は長期的な過大評価を修正し、株価利益倍率は 15 倍に戻り、株価は 15 ドルとなった。
→

クラスワイドな信頼を認めるかどうかにとって、不実表示によって株価が上昇したことが重要であり、株価収益率が過大評価されていたかどうかは関係がない。
② 過剰なボラティリティ設例
上の例で、株価が 20 ドルから 40 ドルへ上昇した。過剰なボラティリティのせいで、株価は、1 時間ごとにランダムに 38 ドルから 42 ドルの間で変動していた。不実表示の発覚により株価は 20 ドルに戻ったが、同じ理由で、19 ドルから 21 ドルの間で変動していた。
→

クラスワイドな信頼を認めるかどうかについて、過剰なボラティリティの有無は関係がない。たしかに過剰なボラティリティは利益の機会を生じるが、不実表示によって価格が歪められていたことに変わりはない。
③ 鈍い市場反応設例
上の例で、良い情報に接して株価は 20 ドルから 35 ドルに上昇したが、翌週 1 週間かけて 40 ドルまで上昇した。不実表示が発覚すると株価は 20 ドルに戻った。
→ 不実表示の開示を受けて当該株式を取得した者が、市場価格の歪みの結果、15 ドル
ないし 20 ドル余分に支払った事実には変わりがない。
第 2 に、裁定機会がない（市場が効率的である）ことは、不実表示が市場価格の歪みをもたらさない場合があることを否定するものではない。
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Lucian A. Bebchuk = Allen Ferrell, Rethinking Basic, 69 Bus. Law. 671 (2014).
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① 公表された情報設例
インターネット企業が、四半期収益を公表した。その数日後、サイトへの来訪者数が 75％上昇したとの不実表示を公表。アナリストは来訪者数の情報を分析して、それが企業の収益性に与える影響を分析した。不実表示を公表したときも、それが不実であると発覚した
ときも株価に変化はなかった。
→

この場合、価格の歪みがないからクラスワイドな信頼は与えられない。市場が開示

情報に反応しなかった理由（情報が重要でなかった、四半期収益の情報で株価が決定されていた、市場が虚偽情報を信頼していなかった等）はなんであれ、重要なのは市場価格に歪みが生じたかどうかである。
② 埋没した情報設例
企業が、環境政策に関する公表された報告書（投資家の興味を惹かなかった）の中で、財務情報について不実表示をした。不実表示をしたときも、その発覚のときも、市場価格に変化はなかった。
→

クラスワイドな信頼は与えられない。情報が価格に反映されなかった理由は重要でない。重要なのは市場価格の歪みが生じていないこと。
信頼の推定法理は次のように改訂されるべきである。
(1)

効率的な市場で取引されている証券の価格は、公開され利用可能な会社に関するすべていくつかの情報を反映する。
(2)

したがって、効率的な市場における証券の買主は、購入するに際して、公開情報を当

該市場価格が詐欺的に歪められていないことを、たとえば、 不実表示がなかったとしても異なる価格でないことを信頼したと推定されることができる。
(3) そして、証券の市場が非効率的である詐欺的に歪められていないとき、原告は市場に対する詐欺クラスワイドな信頼の推定を起動させることができない。
（３）判旨の検討
価格影響性（price impact）≒詐欺的歪曲（fraudulent distortion）
多くの学説が主張するように、最高裁は、市場に対する詐欺理論を、市場の効率性を価格影響性に置き換えたものに修正すべきであった。
信頼の推定を認めるという結論は変わらないので、最高裁は Basic 判決の修正を避けた。
→

信頼の推定を受けるためには、市場が効率的であることを、依然として原告側が示す必要がある。

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市場の効率性の証明方法：Cammer v. Bloom, 711 F. Supp. 1264 (1989) 7の 5 要因テスト(1)株式の取引量(2)当該株式をフォローしていたアナリストの数(3)マーケット・メーカーの数(4)S-3 登録要件を充たすかどうか(5)予期しない新事象に対する株価の反応（４）市場の誠実性に対する信頼というレトリック
法廷意見：価値投資家も、いずれは市場価格が情報を反映すると考えて投資している。
反対意見：価値投資家が取引のときに市場の誠実性を信頼していたかどうかが問題。
この議論は、反対意見に分がある。
そもそも市場の誠実性に対する信頼を問題にすること自体、レトリックにすぎない。
現実の市場には市場価格が情報を反映していると考えて取引を行う投資家とそう考えないゆえに取引を行う投資家が併存することは否定できない。
→

不実表示によって影響を受けた市場価格で取引を行えば、不実表示と取引との間の因果関係（取引因果関係）が認められる。

最高裁は、市場の効率性を前提とするという理解の下で Basic 判決を変更しなかったので、レトリックを用いざるを得なかった。
２ クラス認可段階での価格影響性の反証（１）価格影響性（price impact）と損害因果関係
損害因果関係
投資家の取引と彼の被った損失との間の因果関係
損害因果関係があるといえるためには、有価証券の取得時に不実表示によって市場価格が不当に吊上げられていたことを証明するのでは足りない（Dura 判決8）。
← 不実表示の発覚が株価を下落させたことを示す。
価格影響性「被告の不実表示が実際に株価に影響を与えたか」9
Bebchuk = Ferrell, supra note at 27, 池谷・前掲 48－49 頁。
Dura Pharmaceuticals, Inc. v. Broudo, 544 U. S. 336 (2005).
9 HalliburtonⅡ
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← 不実表示の発覚時のイベント・スタディにより確認するのがふつう。

Coffee 教授のコメント10
HalliburtonⅠは、損害因果関係はクラス認可の段階では争えないとした。Halliburton
Ⅱは、これを実質的に変更して、「価格影響性」はクラス認可段階で争えるとした。同じ証拠が損害因果関係の反証にも価格影響性の反証にも使えるのだから、法はいつもラベ
ル貼りの問題である。Fox 教授も、価格影響性と損害因果関係とは実質的に同じ争点であるとする11。
Bebchuk & Ferrell
価格影響性（詐欺的歪曲）と損害因果関係とは異なる。
FDA 承認設例
企業が、FDA が医療機器を承認するだろうという虚偽の公表をした。株価は直ちに 10％上昇した。原告は、不実表示が市場価格に影響を与えたことを証明した。
→

クラスワイドな信頼は認められる。しかし、詐欺的歪曲が経済損失を生じさせたことはまだ証明されていない。Dura 判決は、価格の吊上げだけでは経済損失の近因にならないとする。価格影響性は、損害因果関係の必要条件であるが十分条件ではない。
← 不実表示時のイベント・スタディで詐欺的歪曲を証明できる事例（２）価格影響性の反証の程度
Coffee 教授の設例
訂正情報の開示の際に市場価格が下落したが、その有意性は、通常求められる 95％のレベルではなく 90％のレベルであった。被告は、価格影響性を反証したと認められるか？
Fox 教授のコメント
クラス認可段階での被告による価格影響性の反証について、本案段階での原告による損
害因果関係の立証の同程度のものを求めるとしたら、被告の反証権は意味のないものとJohn C. Coffee Jr., “Death by One Thousand Cuts”, Columbia Law School's Blog on
Corporations and the Capital Markets (June 30, 2014), at
http://clsbluesky.law.columbia.edu/2014/06/30/death-by-one-thousand-cuts/
11 Merritt B. Fox, “Halliburton II: Who Won and Who Lost All Depends on What
Defendants Need to Show to Establish No Impact on Price”, Columbia Law School's
Blog on Corporations and the Capital Markets (June 30, 2014), at
http://clsbluesky.law.columbia.edu/2014/06/30/halliburton-ii-who-won-and-who-lost-alldepends-on-what-defendants-need-to-show-to-establish-no-impact-on-price/
10

13

13
54

なる。すなわち、95%の信頼水準を要求するのでは意味がない。これに対し、原告が損害因果関係の立証ができないであろうことを被告が裁判所に説得することだけで、信頼の推定が反証されるのだとしたら、本判決は被告にとって意味がある。この場合には、価格影響性と実質的に同じ争点である損害因果関係を、クラス認可の段階で、原告に立証責任を負わせて行うことになる。
価格影響性の反証の程度は、下級審裁判例に委ねられた課題である。
（３）不開示の場合とのバランス「不開示」の場合
不開示の対象が存在しないと信頼したことを立証は、ほとんど不可能である。
→ 開示義務の存在と秘匿された事実の重要性の要件の充足 →因果関係あり（判例12）
積極的な不実表示の場合に、クラス認可段階で価格影響性の反証が認められることとアンバランスが生じる。
Bebchuk & Ferrell
詐欺的歪曲の有無を基準とするアプローチを不開示の場合に適用しない理由はない。
統一的なアプローチをとることで、不実開示と不開示のどちらに当たるかという恣意的な区分を解消することになる。
不開示の場合：ある事実が開示されなかったことが市場価格に影響を及ぼし、投資家の取引の原因となっている（取引因果関係が認められる）のだから、価格影響性の反証も認められるべき。
（４）価格影響性と重要性
重要性
合理的な投資家が投資判断にあたって当該表示を重要と考えたこと。
重要：当時、利用可能な情報の総体を大きく変えるかどうかで判断する。
判旨の掲げる価格影響性と重要性の相違は、性質の相違というよりも、クラス認可の段
階で証拠が提出されているかどうかの相違にすぎず、理由づけとして説得的でない。
Bebchuk & Ferrell
価格影響性の反証を認めることは重要性の要件の審理を先取りすることにはならない。
鉱山設例
12

Affiliated Ute Citizens v. United States, 406 U. S. 128 (1972).
14

14
55

アメリカの鉱山会社がオーストラリアに金鉱を所有している。CEO が鉱山を訪れ、鉱山技師と会話をし、帰国後、「鉱山技師と会話をした。金鉱はとても良いと思う（feel great
about the gold mine）」と発言した。株価は 10％上昇した。後になって、当該金鉱で金を産出することが不可能であると判明した。原告は、CEO の虚偽発言と市場に対するインパクトを証明した。
→

クラスワイドな信頼は認められる。しかし、本案段階で、被告は表示の重要性を争う余地がある。なぜなら、事実の争点は、技師が CEO に話した内容はなにか、その内容（情報）は金鉱をどれだけ有望なものにするか、その情報は CEO の発言を導いたかといった点にあるから。市場に対する影響度と、表示が重要な点で誤解を生じるものを含んでいたか
どうかは別問題である。
３ クラス・アクションへの影響
従来、NYSE や Nasdaq で取引されている株式に関するクラス・アクションでは、クラス認可は自動的に与えられてきた。クラス認可段階で、被告は価格影響性を争えるようになるため、クラス認可段階がミニ・トライアル化する。
→ 原告の費用負担は増え、訴訟は減少する可能性がある。
被告は、①棄却の申立て、②クラス認可の申立て、③略式判決の申立ての 3 段階で争うことができるようになる。従来、証券クラス・アクションは略式判決申立ての前後で和解になることが多かったが、それよりも前で争うことが可能になった。
（以上、主として Coffeeのコメントによる）
D&O 保険について。
被告が価格影響性を争えるので、保険者の支払件数は減少するだろうが、価格影響性をめぐる争いが防御費用を増加させるだろう。保険業界において、クラス認可段階における価格影響性のイベント・スタディの費用を付保範囲とすべきかについて議論がされるだろう。
４ 日本法への示唆
信頼の要件、損害因果関係の要件 ⊂ 相当因果関係
明文で信頼の要件を課す条文はなく、証券クラス・アクション制度もない。
因果関係を取引因果関係と損害因果関係を分けて分析することは有用。
信頼、損害因果関係、重要性の概念の相互の関係について、一定の示唆を与えてくれる。

15

15
56

Fischel 教授
市場に対する詐欺理論の論理を受け入れれば、公開市場での証券詐欺事件において、重要性、信頼、因果関係、および損害賠償額を別々に審査する必要はなくなり、不実表示
が市場価格に人為的な影響を与えたかどうかのみが問題になる13。
この議論は市場の効率性を前提としたもの→

信頼の推定を行うには、市場が効率性である必要はなく、不実表示の価格影響性があれば足りるとなると、上記議論はどのような影響を受けるか？
価格影響性があれば、不実表示は重要で、不実表示と損害との間に因果関係が認められ、損害賠償額は価格に対する影響の幅によって決定されるか。
cf. Bebchuk & Ferrell（私見）価格影響性があれば、不実表示の重要性、信頼の要件、損害因果関係を認めてよ
いが、市場が効率的でない限り、価格に対する影響の幅が直ちに損害賠償額になるとはいえない。

Daniel R. Fischel, Use of Modern Finance Theory in Securities Fraud Cases
Involving Actively Traded Securities, 38 Bus. Law. 1, 13 (1982).

13

16

16
57

配布資料

������
���� Erica P. John Fund, Inc. v. Halliburton Co., 131 S. Ct. 2179 (2011) .

(Halliburton�)���� Amgen Inc. v. Connecticut Retirement Plans and Trust Funds, 133 S. Ct. 1184 (2013).
�Amgen����� Halliburton Co. v. Erica P. John Fund, Inc., 133 S. Ct. 1184 (2014).

58(Halliburton�)資料１(Slip Opinion)

OCTOBER TERM, 2010

1

Syllabus
NOTE: Where it is feasible, a syllabus (headnote) will be released, as is
being done in connection with this case, at the time the opinion is issued.
The syllabus constitutes no part of the opinion of the Court but has been
prepared by the Reporter of Decisions for the convenience of the reader.
See United States v. Detroit Timber & Lumber Co., 200 U. S. 321, 337.

SUPREME COURT OF THE UNITED STATES
Syllabus

ERICA P. JOHN FUND, INC., FKA ARCHDIOCESE OFMILWAUKEE SUPPORTING FUND, INC. v.
HALLIBURTON CO. ET AL.
CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR
THE FIFTH CIRCUIT
No. 09–1403.

Argued April 25, 2011—Decided June 6, 2011

Petitioner Erica P. John Fund, Inc. (EPJ Fund), is the lead plaintiff in aputative securities fraud class action filed against Halliburton Co.
and one of its executives (collectively Halliburton). EPJ Fund allegesthat Halliburton made various misrepresentations designed to inflate
the company’s stock price, in violation of §10(b) of the Securities Exchange Act of 1934 and Securities and Exchange Commission Rule10b–5. EPJ Fund also contends that Halliburton later made a number of corrective disclosures that caused the stock price to drop and,
consequently, investors to lose money. EPJ Fund sought to have its
proposed class certified pursuant to Federal Rule of Civil Procedure
23. The District Court found that the suit could proceed as a classaction under Rule 23(b)(3), but for one problem: Fifth Circuit precedent required securities fraud plaintiffs to prove “loss causation”—
i.e., that the defendant’s deceptive conduct caused the investors’
claimed economic loss—in order to obtain class certification. The
District Court concluded that EPJ Fund had failed to satisfy that requirement. The Court of Appeals agreed and affirmed the denial ofclass certification.
Held: Securities fraud plaintiffs need not prove loss causation in orderto obtain class certification. Pp. 3–10.
(a) In order to certify a class under Rule 23(b)(3), a court must find“that the questions of law or fact common to class members predominate over any questions affecting only individual members, and thata class action is superior to other available methods for fairly and efficiently adjudicating the controversy.” Considering whether “ques-

59

2

ERICA P. JOHN FUND, INC. v. HALLIBURTON CO.
Syllabus
tions of law or fact common to class members predominate” begins, ofcourse, with the elements of the underlying cause of action. The elements of a private securities fraud claim based on violations of §10(b)and Rule 10b–5 are: “(1) a material misrepresentation or omission by
the defendant; (2) scienter; (3) a connection between the misrepresentation or omission and the purchase or sale of a security; (4) reliance
upon the misrepresentation or omission; (5) economic loss; and (6)loss causation.” Matrixx Initiatives, Inc. v. Siracusano, 563 U. S. ___,___.
Whether common questions of law or fact predominate in such anaction often turns on the element of reliance. The traditional way aplaintiff can demonstrate reliance is by showing that he was aware of
a company’s statement and engaged in a relevant transaction—e.g.,purchasing common stock—based on that specific misrepresentation.
The Court recognized in Basic Inc. v. Levinson, 485 U. S. 224, however, that “[r]equiring proof of individualized reliance from eachmember of the proposed plaintiff class effectively would” prevent suchplaintiffs “from proceeding with a class action, since individual issues” would “overwhelm[ ] the common ones.” Id., at 242. The Court
in Basic sought to alleviate that concern by permitting plaintiffs toinvoke a rebuttable presumption of reliance based on what is known
as the “fraud-on-the-market” theory. According to that theory, “themarket price of shares traded on well-developed markets reflects all
publicly available information, and, hence, any material misrepresentations.” Id., at 246. Under that doctrine, the Court explained,
one can assume an investor relies on public misstatements wheneverhe “buys or sells stock at the price set by the market.” Id., at 247.
The Court also made clear that the presumption could be rebutted byappropriate evidence. Pp. 3–5.
(b) It is undisputed that securities fraud plaintiffs must prove certain things in order to invoke Basic’s rebuttable presumption of reliance. According to the Court of Appeals, EPJ Fund had to prove theseparate element of loss causation in order to trigger the presumption. That requirement is not justified by Basic or its logic. This
Court has never mentioned loss causation as a precondition for invoking Basic’s rebuttable presumption. Loss causation addresses a matter different from whether an investor relied on a misrepresentation,
presumptively or otherwise, when buying or selling a stock.
The Court has referred to the element of reliance in a private Rule10b–5 action as “transaction causation,” not loss causation. Dura
Pharmaceuticals, Inc. v. Broudo, 544 U. S. 336, 341–342. Consistent
with that description, when considering whether a plaintiff has relied
on a misrepresentation, the Court has typically focused on facts surrounding the investor’s decision to engage in the transaction. Loss

60

Cite as: 563 U. S. ____ (2011)3

Syllabus
causation, by contrast, requires a plaintiff to show that the misrepresentation caused a subsequent economic loss. That has nothing to dowith whether an investor relied on that misrepresentation in the firstplace, either directly or through the fraud-on-the-market theory. The
Court of Appeals’ rule contravenes Basic’s fundamental premise—that an investor presumptively relies on a misrepresentation so longas it was reflected in the market price at the time of his transaction.
Pp. 5–8.
(c) Halliburton concedes that securities fraud plaintiffs should not
be required to prove loss causation in order to invoke Basic’s presumption of reliance. Halliburton nonetheless defends the judgment
below on the ground that the Court of Appeals did not actually require EPJ Fund to prove “loss causation” as the Court has used that
term. According to Halliburton, “loss causation” was shorthand for adifferent analysis. The lower court’s actual inquiry, Halliburton insists, was whether EPJ Fund had demonstrated “price impact”—that
is, whether the alleged misrepresentations affected the market pricein the first place.
The Court does not accept Halliburton’s interpretation of the Courtof Appeals’ opinion. Loss causation is a familiar and distinct concept
in securities law; it is not price impact. Whatever Halliburton thinks
the Court of Appeals meant to say, what it said was loss causation.
The Court takes the Court of Appeals at its word. Based on thosewords, the decision below cannot stand. Pp. 8–9.
597 F. 3d 330, vacated and remanded.
ROBERTS, C. J., delivered the opinion for a unanimous Court.

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1

Opinion of the Court
NOTICE: This opinion is subject to formal revision before publication in the
preliminary print of the United States Reports. Readers are requested to
notify the Reporter of Decisions, Supreme Court of the United States, Washington, D. C. 20543, of any typographical or other formal errors, in orderthat corrections may be made before the preliminary print goes to press.

SUPREME COURT OF THE UNITED STATES_________________

No. 09–1403_________________ERICA P. JOHN FUND, INC., FKA ARCHDIOCESEOF MILWAUKEE SUPPORTING FUND, INC.,
PETITIONER v. HALLIBURTON CO. ET AL.
ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF
APPEALS FOR THE FIFTH CIRCUIT[June 6, 2011]

CHIEF JUSTICE ROBERTS delivered the opinion of the
Court.
To prevail on the merits in a private securities fraud
action, investors must demonstrate that the defendant’s
deceptive conduct caused their claimed economic loss.
This requirement is commonly referred to as “loss causation.” The question presented in this case is whether
securities fraud plaintiffs must also prove loss causationin order to obtain class certification. We hold that theyneed not.
I
Petitioner Erica P. John Fund, Inc. (EPJ Fund), is thelead plaintiff in a putative securities fraud class action
filed against Halliburton Co. and one of its executives(collectively Halliburton). The suit was brought on behalfof all investors who purchased Halliburton common stock
between June 3, 1999, and December 7, 2001.
EPJ Fund alleges that Halliburton made various misrepresentations designed to inflate its stock price, in violation of §10(b) of the Securities Exchange Act of 1934 and62

2

ERICA P. JOHN FUND, INC. v. HALLIBURTON CO.
Opinion of the Court

Securities and Exchange Commission Rule 10b–5. See 48
Stat. 891, 15 U. S. C. §78j(b); 17 CFR §240.10b–5 (2010).
The complaint asserts that Halliburton deliberately madefalse statements about (1) the scope of its potential liability in asbestos litigation, (2) its expected revenue fromcertain construction contracts, and (3) the benefits of its
merger with another company. EPJ Fund contends thatHalliburton later made a number of corrective disclosuresthat caused its stock price to drop and, consequently,
investors to lose money.
After defeating a motion to dismiss, EPJ Fund sought tohave its proposed class certified pursuant to Federal Ruleof Civil Procedure 23. The parties agreed, and the District
Court held, that EPJ Fund satisfied the general requirements for class actions set out in Rule 23(a): The class was
sufficiently numerous, there were common questions oflaw or fact, the claims of the representative parties weretypical, and the representative parties would fairly andadequately protect the interests of the class. See App. to
Pet. for Cert. 3a.
The District Court also found that the action could
proceed as a class action under Rule 23(b)(3), but for one
problem: Circuit precedent required securities fraud plaintiffs to prove “loss causation” in order to obtain class certification. Id., at 4a, and n. 2 (citing Oscar Private Equity
Invs. v. Allegiance Telecom, Inc., 487 F. 3d 261, 269 (CA52007)). As the District Court explained, loss causation is
the “ ‘causal connection between the material misrepresentation and the [economic] loss’ ” suffered by investors.
App. to Pet. for Cert. 5a, and n. 3 (quoting Dura Pharmaceuticals, Inc. v. Broudo, 544 U. S. 336, 342 (2005)). After
reviewing the alleged misrepresentations and corrective
disclosures, the District Court concluded that it could notcertify the class in this case because EPJ Fund had “failed
to establish loss causation with respect to any” of its
claims. App. to Pet. for Cert. 54a. The court made clear,

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Opinion of the Court

however, that absent “this stringent loss causation requirement,” it would have granted the Fund’s certification
request. Ibid.
The Court of Appeals affirmed the denial of class certification. See 597 F. 3d 330 (CA5 2010). It confirmed that,“[i]n order to obtain class certification on its claims, [EPJFund] was required to prove loss causation, i.e., that thecorrected truth of the former falsehoods actually caused
the stock price to fall and resulted in the losses.” Id., at334. Like the District Court, the Court of Appeals concluded that EPJ Fund had failed to meet the “requirements for proving loss causation at the class certification
stage.” Id., at 344.
We granted the Fund’s petition for certiorari, 562 U. S.
___ (2011), to resolve a conflict among the Circuits as towhether securities fraud plaintiffs must prove loss causation in order to obtain class certification. Compare 597
F. 3d, at 334 (case below), with In re Salomon Analyst
Metromedia Litigation, 544 F. 3d 474, 483 (CA2 2008) (notrequiring investors to prove loss causation at class certification stage); Schleicher v. Wendt, 618 F. 3d 679, 687 (CA72010) (same); In re DVI, Inc. Securities Litigation, No. 08–
8033 etc., 2011 WL 1125926, *7 (CA3, Mar. 29, 2011)(same; decided after certiorari was granted).
II
EPJ Fund contends that the Court of Appeals erred byrequiring proof of loss causation for class certification. We
agree.
A
As noted, the sole dispute here is whether EPJ Fundsatisfied the prerequisites of Rule 23(b)(3). In order tocertify a class under that Rule, a court must find “that thequestions of law or fact common to class members predominate over any questions affecting only individual64

4ERICA P. JOHN FUND, INC. v. HALLIBURTON CO.
Opinion of the Court

members, and that a class action is superior to otheravailable methods for fairly and efficiently adjudicating
the controversy.” Fed. Rule Civ. Proc. 23(b)(3). Considering whether “questions of law or fact common to classmembers predominate” begins, of course, with the elements of the underlying cause of action. The elements of a
private securities fraud claim based on violations of §10(b)and Rule 10b–5 are: “ ‘(1) a material misrepresentation oromission by the defendant; (2) scienter; (3) a connection
between the misrepresentation or omission and the purchase or sale of a security; (4) reliance upon the misrepresentation or omission; (5) economic loss; and (6) losscausation.’ ” Matrixx Initiatives, Inc. v. Siracusano, 563
U. S. ___, ___ (2011) (slip op., at 9) (quoting Stoneridge
Investment Partners, LLC v. Scientific-Atlanta, Inc., 552
U. S. 148, 157 (2008)).
Whether common questions of law or fact predominate
in a securities fraud action often turns on the element of
reliance. The courts below determined that EPJ Fund had
to prove the separate element of loss causation in order toestablish that reliance was capable of resolution on acommon, classwide basis.
“Reliance by the plaintiff upon the defendant’s deceptive
acts is an essential element of the §10(b) private cause ofaction.” Stoneridge, supra, at 159. This is because proof ofreliance ensures that there is a proper “connection between a defendant’s misrepresentation and a plaintiff’s
injury.” Basic Inc. v. Levinson, 485 U. S. 224, 243 (1988).
The traditional (and most direct) way a plaintiff candemonstrate reliance is by showing that he was awareof a company’s statement and engaged in a relevanttransaction—e.g., purchasing common stock—based onthat specific misrepresentation. In that situation, theplaintiff plainly would have relied on the company’s deceptive conduct. A plaintiff unaware of the relevant statement, on the other hand, could not establish reliance on

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5

Opinion of the Court

that basis.
We recognized in Basic, however, that limiting proof ofreliance in such a way “would place an unnecessarily
unrealistic evidentiary burden on the Rule 10b–5 plaintiff
who has traded on an impersonal market.” Id., at 245.
We also observed that “[r]equiring proof of individualized
reliance from each member of the proposed plaintiff classeffectively would” prevent such plaintiffs “from proceedingwith a class action, since individual issues” would “overwhelm[ ] the common ones.” Id., at 242.
The Court in Basic sought to alleviate those related
concerns by permitting plaintiffs to invoke a rebuttablepresumption of reliance based on what is known as the“fraud-on-the-market” theory. According to that theory,“the market price of shares traded on well-developed
markets reflects all publicly available information, and,hence, any material misrepresentations.” Id., at 246.
Because the market “transmits information to the investor
in the processed form of a market price,” we can assume,
the Court explained, that an investor relies on public
misstatements whenever he “buys or sells stock at theprice set by the market.” Id., at 244, 247 (internal quotation marks omitted); see also Stoneridge, supra, at 159;
Dura Pharmaceuticals, 544 U. S., at 341–342. The Court
also made clear that the presumption was just that, andcould be rebutted by appropriate evidence. See Basic,supra, at 248.
B
It is undisputed that securities fraud plaintiffs must
prove certain things in order to invoke Basic’s rebuttablepresumption of reliance. It is common ground, for example, that plaintiffs must demonstrate that the alleged
misrepresentations were publicly known (else how would
the market take them into account?), that the stock tradedin an efficient market, and that the relevant transaction

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ERICA P. JOHN FUND, INC. v. HALLIBURTON CO.
Opinion of the Court

took place “between the time the misrepresentations weremade and the time the truth was revealed.” Basic, 485
U. S., at 248, n. 27; id., at 241–247; see also Stoneridge,
supra, at 159.
According to the Court of Appeals, EPJ Fund also had toestablish loss causation at the certification stage to “trigger the fraud-on-the-market presumption.” 597 F. 3d, at
335 (internal quotation marks omitted); see ibid. (EPJ
Fund must “establish a causal link between the allegedfalsehoods and its losses in order to invoke the fraud-onthe-market presumption”). The court determined that, inorder to invoke a rebuttable presumption of reliance, EPJ
Fund needed to prove that the decline in Halliburton’s
stock was “because of the correction to a prior misleadingstatement” and “that the subsequent loss could not otherwise be explained by some additional factors revealed thento the market.” Id., at 336 (emphasis deleted). This is theloss causation requirement as we have described it. See
Dura Pharmaceuticals, supra, at 342; see also 15 U. S. C.
§78u–4(b)(4).
The Court of Appeals’ requirement is not justified by
Basic or its logic. To begin, we have never before mentioned loss causation as a precondition for invoking Basic’s
rebuttable presumption of reliance. The term “loss causation” does not even appear in our Basic opinion. And forgood reason: Loss causation addresses a matter different
from whether an investor relied on a misrepresentation,
presumptively or otherwise, when buying or selling a
stock.
We have referred to the element of reliance in a private Rule 10b–5 action as “transaction causation,” not losscausation. Dura Pharmaceuticals, supra, at 341–342(citing Basic, supra, at 248–249). Consistent with that
description, when considering whether a plaintiff has
relied on a misrepresentation, we have typically focusedon facts surrounding the investor’s decision to engage in67

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Opinion of the Court

the transaction. See Dura Pharmaceuticals, supra, at
342. Under Basic’s fraud-on-the-market doctrine, an investor presumptively relies on a defendant’s misrepresentation if that “information is reflected in [the] market
price” of the stock at the time of the relevant transaction.
See Basic, 485 U. S., at 247.
Loss causation, by contrast, requires a plaintiff to showthat a misrepresentation that affected the integrity of themarket price also caused a subsequent economic loss. As
we made clear in Dura Pharmaceuticals, the fact that a
stock’s “price on the date of purchase was inflated becauseof [a] misrepresentation” does not necessarily mean thatthe misstatement is the cause of a later decline in value.
544 U. S., at 342 (emphasis deleted; internal quotation
marks omitted). We observed that the drop could insteadbe the result of other intervening causes, such as “changed
economic circumstances, changed investor expectations,
new industry-specific or firm-specific facts, conditions, orother events.” Id., at 342–343. If one of those factors were
responsible for the loss or part of it, a plaintiff would not
be able to prove loss causation to that extent. This is true
even if the investor purchased the stock at a distorted
price, and thereby presumptively relied on the misrepresentation reflected in that price.
According to the Court of Appeals, however, an inability
to prove loss causation would prevent a plaintiff frominvoking the rebuttable presumption of reliance. Such arule contravenes Basic’s fundamental premise—that an
investor presumptively relies on a misrepresentation solong as it was reflected in the market price at the time of
his transaction. The fact that a subsequent loss may havebeen caused by factors other than the revelation of a misrepresentation has nothing to do with whether an investor
relied on the misrepresentation in the first place, either
directly or presumptively through the fraud-on-the-market
theory. Loss causation has no logical connection to the68

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ERICA P. JOHN FUND, INC. v. HALLIBURTON CO.
Opinion of the Court

facts necessary to establish the efficient market predicate
to the fraud-on-the-market theory.
The Court of Appeals erred by requiring EPJ Fundto show loss causation as a condition of obtaining classcertification.
C
Halliburton concedes that securities fraud plaintiffs
should not be required to prove loss causation in order to
invoke Basic’s presumption of reliance or otherwiseachieve class certification. See Tr. of Oral Arg. 26–29.
Halliburton nonetheless defends the judgment below on
the ground that the Court of Appeals did not actuallyrequire plaintiffs to prove “loss causation” as we have usedthat term. See id., at 27 (“it’s not loss causation as thisCourt knows it in Dura”). According to Halliburton, “losscausation” was merely “shorthand” for a different analysis.
Brief for Respondents 18. The lower court’s actual inquiry, Halliburton insists, was whether EPJ Fund had
demonstrated “price impact”—that is, whether the alleged
misrepresentations affected the market price in the firstplace. See, e.g., id., at 16–19, 24–27, 50–51; see also Tr. of
Oral Arg. 27 (stating that the Court of Appeals’ “test is
simply price impact” and that EPJ Fund’s “only burden
under the Fifth Circuit case law was to show priceimpact”).*“Price impact” simply refers to the effect of a misrepresentation on a stock price. Halliburton’s theory is that if a——————* Halliburton further concedes that, even if its conception of what the
Court of Appeals meant by “loss causation” is correct, the Court ofAppeals erred by placing the initial burden on EPJ Fund. See Tr. of
Oral Arg. 29 (“We agree . . . that the Fifth Circuit put the initial burdenof production on the plaintiff, and that’s contrary to Basic”). According
to Halliburton, a plaintiff must prove price impact only after Basic’s
presumption has been successfully rebutted by the defendant. Tr. of
Oral Arg. 28, 38–40. We express no views on the merits of such aframework.

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Opinion of the Court

misrepresentation does not affect market price, an investor cannot be said to have relied on the misrepresentation
merely because he purchased stock at that price. If theprice is unaffected by the fraud, the price does not reflect
the fraud.
We do not accept Halliburton’s wishful interpretation of
the Court of Appeals’ opinion. As we have explained, losscausation is a familiar and distinct concept in securities
law; it is not price impact. While the opinion below may
include some language consistent with a “price impact”
approach, see, e.g., 597 F. 3d, at 336, we simply cannot
ignore the Court of Appeals’ repeated and explicit references to “loss causation,” see id., at 334 (three times), 334
n. 2, 335, 335 n. 10 (twice), 335 n. 11, 336, 336 n. 19, 336
n. 20, 337, 338, 341 (twice), 341 n. 46, 342 n. 47, 343, 344(three times).
Whatever Halliburton thinks the Court of Appeals
meant to say, what it said was loss causation: “[EPJ Fund]was required to prove loss causation, i.e., that the corrected truth of the former falsehoods actually caused thestock price to fall and resulted in the losses.” 597 F. 3d, at
334; see id., at 335 (“we require plaintiffs to establish losscausation in order to trigger the fraud-on-the-market
presumption” (internal quotation marks omitted)). We
take the Court of Appeals at its word. Based on thosewords, the decision below cannot stand.
***Because we conclude the Court of Appeals erred byrequiring EPJ Fund to prove loss causation at the certification stage, we need not, and do not, address any otherquestion about Basic, its presumption, or how and when it
may be rebutted. To the extent Halliburton has preserved
any further arguments against class certification, they
may be addressed in the first instance by the Court ofAppeals on remand.

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ERICA P. JOHN FUND, INC. v. HALLIBURTON CO.
Opinion of the Court

The judgment of the Court of Appeals is vacated, andthe case is remanded for further proceedings consistent
with this opinion.
It is so ordered.

71

資料２
(Slip Opinion)

OCTOBER TERM, 2012

1

Syllabus
NOTE: Where it is feasible, a syllabus (headnote) will be released, as is
being done in connection with this case, at the time the opinion is issued.
The syllabus constitutes no part of the opinion of the Court but has been
prepared by the Reporter of Decisions for the convenience of the reader.
See United States v. Detroit Timber & Lumber Co., 200 U. S. 321, 337.

SUPREME COURT OF THE UNITED STATES
Syllabus

AMGEN INC. ET AL. v. CONNECTICUT RETIREMENT
PLANS AND TRUST FUNDSCERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR
THE NINTH CIRCUIT
No. 11–1085.

Argued November 5, 2012—Decided February 27, 2013

To recover damages in a private securities-fraud action under §10(b) of
the Securities Exchange Act of 1934 and Securities and Exchange
Commission Rule 10b–5, a plaintiff must prove, among other things,
reliance on a material misrepresentation or omission made by the defendant. Matrixx Initiatives, Inc. v. Siracusano, 563 U. S. ___, ___.
Requiring proof of direct reliance “would place an unnecessarily unrealistic evidentiary burden on [a] plaintiff who has traded on an impersonal market.” Basic Inc. v. Levinson, 485 U. S. 224, 245. Thus,
this Court has endorsed a “fraud-on-the-market” theory, which permits securities-fraud plaintiffs to invoke a rebuttable presumption ofreliance on public, material misrepresentations regarding securities
traded in an efficient market. Id., at 241–249. The fraud-on-themarket theory facilitates the certification of securities-fraud class actions by permitting reliance to be proved on a classwide basis.
Invoking the fraud-on-the-market theory, respondent Connecticut
Retirement Plans and Trust Funds (Connecticut Retirement) sought
certification of a securities-fraud class action under Federal Rule ofCivil Procedure 23(b)(3) against biotechnology company Amgen Inc.
and several of its officers (collectively, Amgen). The District Court
certified the class, and the Ninth Circuit affirmed. The Ninth Circuit
rejected Amgen’s argument that Connecticut Retirement was required to prove the materiality of Amgen’s alleged misrepresentations and omissions before class certification in order to satisfy Rule23(b)(3)’s requirement that “questions of law or fact common to classmembers predominate over any questions affecting only individual
members.” The Ninth Circuit also held that the District Court did
not err in refusing to consider rebuttal evidence that Amgen had pre-72

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AMGEN, INC. v. CONNECTICUT RETIREMENT PLANS
AND TRUST FUNDS
Syllabus
sented on the issue of materiality at the class-certification stage.

Held: Proof of materiality is not a prerequisite to certification of a securities-fraud class action seeking money damages for alleged violationsof §10(b) and Rule 10b–5. Pp. 9–26.
(a) The pivotal inquiry in this case is whether proof of materiality
is needed to ensure that the questions of law or fact common to theclass will “predominate over any questions affecting only individual
members” as the litigation progresses. For two reasons, the answer
to this question is “no.” First, because materiality is judged according to an objective standard, it can be proved through evidence common to the class. TSC Industries, Inc. v. Northway, Inc., 426 U. S.
438, 445. Thus, it is a common question for Rule 23(b)(3) purposes.
Second, a failure of proof on the common question of materiality
would not result in individual questions predominating. Instead, itwould end the case, for materiality is an essential element of a securities-fraud claim. Pp. 9–14.
(b) Amgen’s arguments to the contrary are unpersuasive. Pp. 14–24.
(1) Amgen points to the Court’s statement in Erica P. John
Fund, Inc. v. Halliburton Co., 563 U. S. ___, ___, that “securities
fraud plaintiffs must prove certain things in order to invoke Basic’s
rebuttable presumption of reliance,” including “that the alleged misrepresentations were publicly known . . . , that the stock traded in an
efficient market, and that the relevant transaction took place ‘between the time the misrepresentations were made and the time thetruth was revealed.’ ” If these fraud-on-the-market predicates must
be proved before class certification, Amgen contends, materiality—
another fraud-on-the-market predicate—should be treated no differently. The Court disagrees. The requirement that a putative classrepresentative establish that it executed trades “between the timethe misrepresentations were made and the time the truth was revealed” relates primarily to the Rule 23(a)(3) and (a)(4) inquiries into
typicality and adequacy of representation, not to the Rule 23(b)(3)predominance inquiry. And unlike materiality, market efficiency andthe public nature of the alleged misrepresentations are not indispensable elements of a Rule 10–5 claim. While the failure of common,classwide proof of market efficiency or publicity leaves open the prospect of individualized proof of reliance, the failure of common proof
on the issue of materiality ends the case for all class members.
Pp. 15–18.
(2) Amgen also contends that “policy considerations” militate infavor of requiring precertification proof of materiality. Because classcertification can exert substantial pressure on the defendant to settle
rather than risk ruinous liability, Amgen asserts, materiality may

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Syllabus
never be addressed by a court if it is not required to be evaluated at
the class-certification stage. In this regard, however, materiality
does not differ from other essential elements of a Rule 10b–5 claim,
notably, the requirements that the statements or omissions on which
the plaintiff ’s claims are based were false or misleading and that thealleged statements or omissions caused the plaintiff to suffer economic loss. Significantly, while addressing the settlement pressures associated with securities-fraud class actions, Congress has rejectedcalls to undo the fraud-on-the-market theory. And contrary toAmgen’s argument that requiring proof of materiality before classcertification would conserve judicial resources, Amgen’s position
would necessitate time and resource intensive mini-trials on materiality at the class-certification stage. Pp. 18–22.
(c) Also unavailing is Amgen’s claim that the District Court erredby refusing to consider the rebuttal evidence Amgen proffered in opposing Connecticut Retirement’s class-certification motion. The
Ninth Circuit concluded, and Amgen does not contest, that Amgen’s
rebuttal evidence aimed to prove that the misrepresentations andomissions alleged in Connecticut Retirement’s complaint were immaterial. The potential immateriality of Amgen’s alleged misrepresentations and omissions, however, is no barrier to finding that common
questions predominate. Just as a plaintiff class’s inability to provemateriality creates no risk that individual questions will predominate, a definitive rebuttal on the issue of materiality would not undermine the predominance of questions common to the class. Pp. 24–
26.
660 F. 3d 1170, affirmed.
GINSBURG, J., delivered the opinion of the Court, in which ROBERTS,
C. J., and BREYER, ALITO, SOTOMAYOR, and KAGAN, JJ., joined. ALITO,
J., filed a concurring opinion. SCALIA, J., filed a dissenting opinion.
THOMAS, J., filed a dissenting opinion, in which KENNEDY, J., joined,
and in which SCALIA, J., joined except for Part I–B.

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1

Opinion of the Court
NOTICE: This opinion is subject to formal revision before publication in the
preliminary print of the United States Reports. Readers are requested to
notify the Reporter of Decisions, Supreme Court of the United States, Washington, D. C. 20543, of any typographical or other formal errors, in orderthat corrections may be made before the preliminary print goes to press.

SUPREME COURT OF THE UNITED STATES_________________

No. 11–1085_________________AMGEN INC., ET AL., PETITIONERS v. CONNECTICUTRETIREMENT PLANS AND TRUST FUNDSON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF
APPEALS FOR THE NINTH CIRCUIT[February 27, 2013]JUSTICE GINSBURG delivered the opinion of the Court.
This case involves a securities-fraud complaint filed
by Connecticut Retirement Plans and Trust Funds (Connecticut Retirement) against biotechnology company
Amgen Inc. and several of its officers (collectively, Amgen).
Seeking class-action certification under Federal Rule ofCivil Procedure 23, Connecticut Retirement invoked the“fraud-on-the-market” presumption endorsed by this Court
in Basic Inc. v. Levinson, 485 U. S. 224 (1988), and recognized most recently in Erica P. John Fund, Inc. v. Halliburton Co., 563 U. S. ___ (2011). The fraud-on-the-market
premise is that the price of a security traded in an efficient
market will reflect all publicly available information about
a company; accordingly, a buyer of the security may bepresumed to have relied on that information in purchasing
the security.
Amgen has conceded the efficiency of the market forthe securities at issue and has not contested the publiccharacter of the allegedly fraudulent statements on which
Connecticut Retirement’s complaint is based. Nor does
Amgen here dispute that Connecticut Retirement meets75

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AMGEN INC. v. CONNECTICUT RETIREMENT PLANS
AND TRUST FUNDS
Opinion of the Court

all of the class-action prerequisites stated in Rule 23(a):(1) the alleged class “is so numerous that joinder of all
members is impracticable”; (2) “there are questions of law
or fact common to the class”; (3) Connecticut Retirement’s
claims are “typical of the claims . . . of the class”; and (4)Connecticut Retirement will “fairly and adequately protect
the interests of the class.”
The issue presented concerns the requirement stated inRule 23(b)(3) that “the questions of law or fact common toclass members predominate over any questions affecting
only individual members.” Amgen contends that to meetthe predominance requirement, Connecticut Retirement
must do more than plausibly plead that Amgen’s alleged
misrepresentations and misleading omissions materiallyaffected Amgen’s stock price. According to Amgen, certification must be denied unless Connecticut Retirement
proves materiality, for immaterial misrepresentations oromissions, by definition, would have no impact on Amgen’s
stock price in an efficient market.
While Connecticut Retirement certainly must provemateriality to prevail on the merits, we hold that suchproof is not a prerequisite to class certification. Rule23(b)(3) requires a showing that questions common to theclass predominate, not that those questions will be answered, on the merits, in favor of the class. Because materiality is judged according to an objective standard, themateriality of Amgen’s alleged misrepresentations andomissions is a question common to all members of theclass Connecticut Retirement would represent. The alleged misrepresentations and omissions, whether material
or immaterial, would be so equally for all investors composing the class. As vital, the plaintiff class’s inability toprove materiality would not result in individual questions
predominating. Instead, a failure of proof on the issueof materiality would end the case, given that materiality
is an essential element of the class members’ securities-

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3

Opinion of the Court

fraud claims. As to materiality, therefore, the class isentirely cohesive: It will prevail or fail in unison. In no
event will the individual circumstances of particular classmembers bear on the inquiry.
Essentially, Amgen, also the dissenters from today’s
decision, would have us put the cart before the horse. To
gain certification under Rule 23(b)(3), Amgen and thedissenters urge, Connecticut Retirement must first establish that it will win the fray. But the office of a Rule23(b)(3) certification ruling is not to adjudicate the case;rather, it is to select the “metho[d]” best suited to adjudication of the controversy “fairly and efficiently.”
I
A
This case involves the interaction between federal
securities-fraud laws and Rule 23’s requirements forclass certification. To obtain certification of a class action for money damages under Rule 23(b)(3), a plaintiff
must satisfy Rule 23(a)’s above-mentioned prerequisitesof numerosity, commonality, typicality, and adequacy ofrepresentation, see supra, at 1–2, and must also establishthat “the questions of law or fact common to class members predominate over any questions affecting only individual members, and that a class action is superior toother available methods for fairly and efficiently adjudicating the controversy.” To recover damages in a private
securities-fraud action under §10(b) of the Securities
Exchange Act of 1934, 48 Stat. 891, as amended, 15
U. S. C. §78j(b) (2006 ed., Supp. V), and Securities andExchange Commission Rule 10b–5, 17 CFR §240.10b–5(2011), a plaintiff must prove “(1) a material misrepresentation or omission by the defendant; (2) scienter; (3) aconnection between the misrepresentation or omission andthe purchase or sale of a security; (4) reliance upon themisrepresentation or omission; (5) economic loss; and (6)774AMGEN INC. v. CONNECTICUT RETIREMENT PLANS
AND TRUST FUNDS
Opinion of the Court

loss causation.” Matrixx Initiatives, Inc. v. Siracusano,
563 U. S. ___, ___ (2011) (slip op., at 9) (internal quotation
marks omitted).
“Reliance,” we have explained, “is an essential elementof the §10(b) private cause of action” because “proof ofreliance ensures that there is a proper connection between
a defendant’s misrepresentation and a plaintiff ’s injury.”
Halliburton, 563 U. S., at ___ (slip op., at 4) (internal
quotation marks omitted). “The traditional (and mostdirect) way” for a plaintiff to demonstrate reliance “is byshowing that he was aware of a company’s statement andengaged in a relevant transaction . . . based on that specificmisrepresentation.” Ibid. We have recognized, however,that requiring proof of direct reliance “would place an
unnecessarily unrealistic evidentiary burden on [a] plaintiff who has traded on an impersonal market.” Basic, 485
U. S., at 245. Accordingly, in Basic the Court endorsed the“fraud-on-the-market” theory, which permits certain Rule10b–5 plaintiffs to invoke a rebuttable presumption ofreliance on material misrepresentations aired to the general public. Id., at 241–249.1
The fraud-on-the-market theory rests on the premisethat certain well developed markets are efficient processors of public information. In such markets, the “market
price of shares” will “reflec[t] all publicly available information.” Id., at 246. Few investors in such markets, ifany, can consistently achieve above-market returns bytrading based on publicly available information alone, forif such above-market returns were readily attainable, it——————
1 Part IV of Justice Blackmun’s opinion in Basic—the part endorsing the fraud-on-the-market theory—was joined by Justices Brennan,
Marshall, and Stevens. Together, these Justices composed a majorityof the quorum of six Justices who participated in the case. See 28
U. S. C. §1 (“The Supreme Court of the United States shall consist of a
Chief Justice of the United States and eight associate justices, any sixof whom shall constitute a quorum.”).

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Opinion of the Court

would mean that market prices were not efficiently incorporating the full supply of public information. See R.
Brealey, S. Myers, & F. Allen, Principles of Corporate
Finance 330 (10th ed. 2011) (“[I]n an efficient market,
there is no way for most investors to achieve consistently
superior rates of return.”).
In Basic, we held that if a market is shown to be efficient, courts may presume that investors who tradedsecurities in that market relied on public, material misrepresentations regarding those securities. See 485 U. S.,
at 245–247. This presumption springs from the very
concept of market efficiency. If a market is generally
efficient in incorporating publicly available information
into a security’s market price, it is reasonable to presume
that a particular public, material misrepresentation will
be reflected in the security’s price. Furthermore, it isreasonable to presume that most investors—knowing thatthey have little hope of outperforming the market in thelong run based solely on their analysis of publicly available information—will rely on the security’s market price as
an unbiased assessment of the security’s value in light ofall public information. Thus, courts may presume thatinvestors trading in efficient markets indirectly rely on
public, material misrepresentations through their “reliance on the integrity of the price set by the market.” Id.,
at 245. “[T]he presumption,” however, is “just that, and[can] be rebutted by appropriate evidence.” Halliburton,
563 U. S., at ___ (slip op., at 5). See also Basic, 485 U. S.,
at 248–249 (providing examples of showings that would
rebut the fraud-on-the-market presumption).
Although fraud on the market is a substantive doctrineof federal securities-fraud law that can be invoked by any
Rule 10b–5 plaintiff, see, e.g., Black v. Finantra Capital,
Inc., 418 F. 3d 203, 209 (CA2 2005); Blackie v. Barrack,
524 F. 2d 891, 908 (CA9 1975), the doctrine has particularsignificance in securities-fraud class actions. Absent the79

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AMGEN INC. v. CONNECTICUT RETIREMENT PLANS
AND TRUST FUNDS
Opinion of the Court

fraud-on-the-market theory, the requirement that Rule10b–5 plaintiffs establish reliance would ordinarily preclude certification of a class action seeking money damages because individual reliance issues would overwhelm
questions common to the class. See Basic, 485 U. S., at242. The fraud-on-the-market theory, however, facilitatesclass certification by recognizing a rebuttable presumptionof classwide reliance on public, material misrepresentations when shares are traded in an efficient market. Ibid.2
B
In its complaint, Connecticut Retirement alleges thatAmgen violated §10(b) and Rule 10b–5 through certain
misrepresentations and misleading omissions regarding
the safety, efficacy, and marketing of two of its flagshipdrugs.3 According to Connecticut Retirement, these misrepresentations and omissions artificially inflated theprice of Amgen’s stock at the time Connecticut Retirement
and numerous other securities buyers purchased thestock. When the truth came to light, Connecticut Retirement asserts, Amgen’s stock price declined, resulting in
financial losses to those who purchased the stock at the
inflated price. In its answer to Connecticut Retirement’s
complaint, Amgen conceded that “[a]t all relevant times,
the market for [its] securities,” which are traded on the
NASDAQ stock exchange, “was an efficient market”; thus,“the market for Amgen’s securities promptly digested
current information regarding Amgen from all publicly——————
2 Althoughdescribing Basic’s adoption of the fraud-on-the-market
presumption of reliance as “questionable,” JUSTICE THOMAS’ dissent
acknowledges that “the Court has not been asked to revisit” that issue.
Post, at 4–5, n. 4. See also post, p. 1 (ALITO, J., concurring).
3 Amgen’s allegedly improper marketing practices have sparked federal and state investigations and several whistleblower lawsuits. See
Dye, Amgen to pay $762 million in drug-marketing case, Washington
Post, Dec. 19, 2012, p. A17.

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Opinion of the Court

available sources and reflected such information in
Amgen’s stock price.” Consolidated Amended Class Action
Complaint ¶¶199–200 in No. CV–07–2536 (CD Cal.);Answer ¶¶199–200.
The District Court granted Connecticut Retirement’s
motion to certify a class action under Rule 23(b)(3) onbehalf of all investors who purchased Amgen stock between the date of the first alleged misrepresentation andthe date of the last alleged corrective disclosure. After
granting Amgen’s request to take an interlocutory appeal
from the District Court’s class-certification order, see Fed.
Rule Civ. Proc. 23(f), the Court of Appeals affirmed. See
660 F. 3d 1170 (CA9 2011).
Amgen raised two arguments on appeal. First, Amgencontended that the District Court erred by certifying the
proposed class without first requiring Connecticut Retirement to prove that Amgen’s alleged misrepresentations
and omissions were material. Second, Amgen argued thatthe District Court erred by refusing to consider certain
rebuttal evidence that Amgen had proffered in opposition
to Connecticut Retirement’s class-certification motion.
This evidence, in Amgen’s view, demonstrated that themarket was well aware of the truth regarding its alleged
misrepresentations and omissions at the time the classmembers purchased their shares.
The Court of Appeals rejected both contentions.
Amgen’s first argument, the Court of Appeals noted, madethe uncontroversial point that immaterial misrepresentations and omissions “by definition [do] not affect . . . stock
price[s] in an efficient market.” Id., at 1175. Thus,
where misrepresentations and omissions are not material,
there is no basis for presuming classwide reliance on
those misrepresentations and omissions through theinformation-processing mechanism of the market price.
“The problem with that argument,” the Court of Appeals observed, is evident: “[B]ecause materiality is an element of81

8AMGEN INC. v. CONNECTICUT RETIREMENT PLANS
AND TRUST FUNDS
Opinion of the Court

the merits of their securities fraud claim, the plaintiffs
cannot both fail to prove materiality yet still have a viableclaim for which they would need to prove reliance individually.” Ibid. The Court of Appeals thus concluded that“proof of materiality is not necessary” to ensure compliance with Rule 23(b)(3)’s requirement that common questions predominate. Id., at 1177.
With respect to Amgen’s second argument, the Court ofAppeals determined that Amgen’s proffered rebuttal
evidence was merely “a method of refuting [the] materiality” of the misrepresentations and omissions alleged
in Connecticut Retirement’s complaint. Ibid. Having already concluded that a securities-fraud plaintiff does notneed to prove materiality before class certification, thecourt similarly held that “the district court correctly refused to consider” Amgen’s rebuttal evidence “at the classcertification stage.” Ibid.
We granted Amgen’s petition for certiorari, 567 U. S. ___(2012), to resolve a conflict among the Courts of Appeals
over whether district courts must require plaintiffs toprove, and must allow defendants to present evidence
rebutting, the element of materiality before certifying aclass action under §10(b) and Rule 10b–5. Compare 660
F. 3d 1170 (case below); and Schleicher v. Wendt, 618 F. 3d679, 687 (CA7 2010) (materiality need not be proved at theclass-certification stage), with In re Salomon Analyst
Metromedia Litigation, 544 F. 3d 474, 484–485, 486, n. 9
(CA2 2008) (plaintiff must prove, and defendant may
present evidence rebutting, materiality before class certification). See also In re DVI, Inc. Securities Litigation, 639
F. 3d 623, 631–632, 637–638 (CA3 2011) (plaintiff need
not prove materiality before class certification, but defendant may present rebuttal evidence on the issue).

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The only issue before us in this case is whether Connecticut Retirement has satisfied Rule 23(b)(3)’s requirementthat “questions of law or fact common to class members
predominate over any questions affecting only individual
members.” Although we have cautioned that a court’sclass-certification analysis must be “rigorous” and may“entail some overlap with the merits of the plaintiff ’s
underlying claim,” Wal-Mart Stores, Inc. v. Dukes, 564
U. S. ___, ___ (2011) (slip op., at 10) (internal quotation
marks omitted), Rule 23 grants courts no license to engage
in free-ranging merits inquiries at the certification stage.
Merits questions may be considered to the extent—butonly to the extent—that they are relevant to determining
whether the Rule 23 prerequisites for class certification
are satisfied. See id., at ___, n. 6 (slip op., at 10, n. 6) (adistrict court has no “ ‘authority to conduct a preliminary
inquiry into the merits of a suit’ ” at class certification
unless it is necessary “to determine the propriety of certification” (quoting Eisen v. Carlisle & Jacquelin, 417 U. S.
156, 177 (1974))); Advisory Committee’s 2003 Note on
subd. (c)(1) of Fed. Rule Civ. Proc. 23, 28 U. S. C. App.,p. 144 (“[A]n evaluation of the probable outcome on the
merits is not properly part of the certification decision.”).
Bearing firmly in mind that the focus of Rule 23(b)(3)
is on the predominance of common questions, we turn toAmgen’s contention that the courts below erred by failingto require Connecticut Retirement to prove the materiality of Amgen’s alleged misrepresentations and omissions
before certifying Connecticut Retirement’s proposed class.
As Amgen notes, materiality is not only an element of theRule 10b–5 cause of action; it is also an essential predicateof the fraud-on-the-market theory. See Basic, 485 U. S., at247 (“[W]here materially misleading statements have been
disseminated into an impersonal, well-developed market

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AND TRUST FUNDS
Opinion of the Court

for securities, the reliance of individual plaintiffs on the
integrity of the market price may be presumed.” (emphasis
added)). That theory, Amgen correctly observes, is premised on the understanding that in an efficient market,
all publicly available information is rapidly incorporated
into, and thus transmitted to investors through, the market price. See id., at 246–247. Because immaterial information, by definition, does not affect market price,
it cannot be relied upon indirectly by investors who, as
the fraud-on-the-market theory presumes, rely on the market price’s integrity. Therefore, the fraud-on-the-market
theory cannot apply absent a material misrepresentationor omission. And without the fraud-on-the-market theory,
the element of reliance cannot be proved on a classwide
basis through evidence common to the class. See id., at242. It thus follows, Amgen contends, that materiality
must be proved before a securities-fraud class action canbe certified.
Contrary to Amgen’s argument, the key question in thiscase is not whether materiality is an essential predicate of
the fraud-on-the-market theory; indisputably it is.4 Instead, the pivotal inquiry is whether proof of materiality isneeded to ensure that the questions of law or fact common
to the class will “predominate over any questions affecting
only individual members” as the litigation progresses.
Fed. Rule Civ. Proc. 23(b)(3). For two reasons, the answer
to this question is clearly “no.”——————
4 We agree with JUSTICE THOMAS that “[m]ateriality was central tothe development, analysis, and adoption of the fraud-on-the-market
theory both before Basic and in Basic itself.” Post, at 18. We disagree,
however, that the history of the fraud-on-the-market theory’s development “confirms that materiality must be proved at the time that thetheory is invoked—i.e., at certification.” Ibid. As explained below, seeinfra this page and 11–13, proof of materiality is not required prior toclass certification because such proof is not necessary to ensure satisfaction of Rule 23(b)(3)’s predominance requirement.

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First, because “[t]he question of materiality . . . is anobjective one, involving the significance of an omitted or
misrepresented fact to a reasonable investor,” materiality
can be proved through evidence common to the class. TSC
Industries, Inc. v. Northway, Inc., 426 U. S. 438, 445(1976). Consequently, materiality is a “common questio[n]” for purposes of Rule 23(b)(3). Basic, 485 U. S., at242 (listing “materiality” as one of the questions common
to the Basic class members).
Second, there is no risk whatever that a failure of proof
on the common question of materiality will result in individual questions predominating. Because materiality isan essential element of a Rule 10b–5 claim, see Matrixx
Initiatives, 563 U. S., at ___ (slip op., at 9), Connecticut
Retirement’s failure to present sufficient evidence of materiality to defeat a summary-judgment motion or to prevailat trial would not cause individual reliance questions to
overwhelm the questions common to the class. Instead,the failure of proof on the element of materiality would
end the case for one and for all; no claim would remain in which individual reliance issues could potentially
predominate.
Totally misapprehending our essential point, JUSTICETHOMAS’ dissent asserts that our “entire argument isbased on the assumption that the fraud-on-the-market
presumption need not be shown at certification because it
will be proved later on the merits.” Post, at 11, n. 9. Our
position is not so based. We rest, instead, entirely on the
text of Rule 23(b)(3), which provides for class certification
if “the questions of law or fact common to class members
predominate over any questions affecting only individual
members.” A failure of proof on the common question ofmateriality ends the litigation and thus will never cause
individual questions of reliance or anything else to overwhelm questions common to the class. Therefore, under
the plain language of Rule 23(b)(3), plaintiffs are not

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required to prove materiality at the class-certification
stage. In other words, they need not, at that threshold,prove that the predominating question will be answered intheir favor.
JUSTICE THOMAS urges that a plaintiff seeking classcertification “must show that the elements of [her] claim
are susceptible to classwide proof.” Post, at 7. See also
post, at 11 (criticizing the Court for failing to focus its
analysis on “whether the element of reliance is susceptible
to classwide proof ”). From this premise, JUSTICE THOMAS
concludes that Rule 10b–5 plaintiffs must prove materiality before class certification because (1) “materiality is anecessary component of fraud on the market,” and (2)without fraud on the market, the Rule 10b–5 element of
reliance is not “susceptible of a classwide answer.” Post,at 6, 10–11. See also post, at 12 (“[I]f a plaintiff wishes touse Basic’s presumption to prove that reliance is a common question, he must establish the entire presumption,
including materiality, at the class certification stage.”).
Rule 23(b)(3), however, does not require a plaintiff
seeking class certification to prove that each “elemen[t] of[her] claim [is] susceptible to classwide proof.” Post, at 7.
What the rule does require is that common questions“predominate over any questions affecting only individual[class] members.” Fed. Rule Civ. Proc. 23(b)(3) (emphasis
added). Nowhere does JUSTICE THOMAS explain how, inan action invoking the Basic presumption, a plaintiff
class’s failure to prove an essential element of its claim forrelief will result in individual questions predominatingover common ones. Absent proof of materiality, the claimof the Rule 10b–5 class will fail in its entirety; there will
be no remaining individual questions to adjudicate.
Consequently, proof of materiality is not required toestablish that a proposed class is “sufficiently cohesive
to warrant adjudication by representation”—the focus of
the predominance inquiry under Rule 23(b)(3). Amchem

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Products, Inc. v. Windsor, 521 U. S. 591, 623 (1997). No
doubt a clever mind could conjure up fantastic scenarios inwhich an individual investor might rely on immaterial
information (think of the superstitious investor who sells
her securities based on a CEO’s statement that a black catcrossed the CEO’s path that morning). But such objectively
unreasonable reliance does not give rise to a Rule 10b–5
claim. See TSC Industries, 426 U. S., at 445 (materiality
is judged by an objective standard). Thus, “the individualized questions of reliance,” post, at 9, n. 8, that hypothetically might arise when a failure of proof on the issue ofmateriality dooms the fraud-on-the-market class are far
more imaginative than real. Such “individualized questions” do not undermine class cohesion and thus cannot be
said to “predominate” for purposes of Rule 23(b)(3).5
Because the question of materiality is common to theclass, and because a failure of proof on that issue would
not result in questions “affecting only individual members”
predominating, Fed. Rule Civ. Proc. 23(b)(3), Connecticut
Retirement was not required to prove the materiality ofAmgen’s alleged misrepresentations and omissions at theclass-certification stage. This is not a case in which theasserted problem—i.e., that the plaintiff class cannot
prove materiality—“exhibits some fatal dissimilarity”
among class members that would make use of the classaction device inefficient or unfair. Nagareda, Class Certification in the Age of Aggregate Proof, 84 N. Y. U. L. Rev.
97, 107 (2009). Instead, what Amgen alleges is “a fatal
similarity—[an alleged] failure of proof as to an element of——————
5 JUSTICE THOMAS is also wrong in arguing that a failure of proof on
the issue of materiality would demonstrate that a Rule 10b–5 classaction “should not have been certified in the first place.” Post, at 2.
Quite the contrary. The fact that such a failure of proof resolves allclass members’ claims once and for all, leaving no individual issues tobe adjudicated, confirms that the original certification decision wasproper.

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the plaintiffs’ cause of action.” Ibid. Such a contention isproperly addressed at trial or in a ruling on a summaryjudgment motion. The allegation should not be resolved indeciding whether to certify a proposed class. Ibid. See
also Schleicher, 618 F. 3d, at 687 (“[W]hether a statement
is materially false is a question common to all class members and therefore may be resolved on a class-wide basis
after certification.”).
B
Insisting that materiality must be proved at the classcertification stage, Amgen relies chiefly on two arguments,
neither of which we find persuasive.6——————
6 Amgen advances a third argument founded on modern economic
research tending to show that market efficiency is not “ ‘a binary, yes orno question.’ ” Brief for Petitioners 32 (quoting Langevoort, Basic at
Twenty: Rethinking Fraud on the Market, 2009 Wis. L. Rev. 151, 167).
Instead, this research suggests, differences in efficiency can exist
within a single market. For example, a market may more readily
process certain forms of widely disseminated and easily digestible
information, such as public merger announcements, than information
more difficult to acquire and understand, such as obscure technicaldata buried in a filing with the Securities and Exchange Commission.
See, e.g., Macey & Miller, Good Finance, Bad Economics: An Analysis of
the Fraud-on-the-Market Theory, 42 Stan. L. Rev. 1059, 1083–1087(1990); Stout, The Mechanisms of Market Inefficiency: An Introduction
to the New Finance, 28 J. Corp. L. 635, 653–656 (2003). Amgen,
however, never clearly explains how this research on market efficiency
bolsters its argument that courts should require precertification proofof materiality. In any event, this case is a poor vehicle for exploring
whatever implications the research Amgen cites may have for the
fraud-on-the-market presumption recognized in Basic. As noted above,see supra, at 6–7, Amgen conceded in its answer that the market for its
securities is “efficient” and thus “promptly digest[s] current information
regarding Amgen from all publicly available sources and reflect[s] suchinformation in Amgen’s stock price.” Consolidated Amended Class
Action Complaint ¶¶199–200; Answer ¶¶199–200. See also App. to Pet.
for Cert. 40a (relying on the admission in Amgen’s answer and an
unchallenged expert report submitted by Connecticut Retirement, theDistrict Court expressly found that the market for Amgen’s stock was88

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1
Amgen points first to our statement in Halliburton that
“securities fraud plaintiffs must prove certain things inorder to invoke Basic’s rebuttable presumption of reliance,” including “that the alleged misrepresentations were
publicly known . . . , that the stock traded in an efficient
market, and that the relevant transaction took place‘between the time the misrepresentations were made andthe time the truth was revealed.’ ” 563 U. S., at ___ (slipop., at 5–6) (quoting Basic, 485 U. S., at 248, n. 27). See
also Dukes, 564 U. S., at ___, n. 6 (slip op., at 11, n. 6)(“[P]laintiffs seeking 23(b)(3) certification [of a securitiesfraud class action] must prove that their shares weretraded on an efficient market.”). If these fraud-on-the-market
predicates must be proved before class certification,Amgen contends, materiality—another fraud-on-themarket predicate—should be treated no differently.
We disagree. As an initial matter, the requirement thata putative class representative establish that it executed
trades “between the time the misrepresentations weremade and the time the truth was revealed” relates primarily to the Rule 23(a)(3) and (a)(4) inquiries into typicality
and adequacy of representation, not to the Rule 23(b)(3)predominance inquiry. Basic, 485 U. S., at 248, n. 27.7 A——————
efficient). Amgen remains bound by that concession. See American
Title Ins. Co. v. Lacelaw Corp., 861 F. 2d 224, 226 (CA9 1988) (“Factual
assertions in pleadings and pretrial orders, unless amended, areconsidered judicial admissions conclusively binding on the party who
made them.”); cf. Christian Legal Soc. Chapter of Univ. of Cal., Hastings College of Law v. Martinez, 561 U. S. ___, ___ (2010) (slip op., at10) (“This Court has . . . refused to consider a party’s argument that
contradicted a joint ‘stipulation [entered] at the outset of th[e] litigation.’ ” (quoting Board of Regents of Univ. of Wis. System v. Southworth,
529 U. S. 217, 226 (2000))). We thus find nothing in the cited researchthat would support requiring precertification proof of materiality in thiscase.
7 As earlier noted, see supra, at 1–2, Amgen does not here contest

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security’s market price cannot be affected by a misrepresentation not yet made, and in an efficient market, amisrepresentation’s impact on market price is quickly
nullified once the truth comes to light. Thus, a plaintiff
whose relevant transactions were not executed between
the time the misrepresentation was made and the time thetruth was revealed cannot be said to have indirectly reliedon the misrepresentation through its reliance on the integrity of the market price.8 Such a plaintiff ’s claims,
therefore, would not be “typical” of the claims of investors
who did trade during the window between misrepresentation and truth revelation. Fed. Rule Civ. Proc. 23(a)(3).
Nor could a court confidently conclude that such a plaintiff
would “fairly and adequately protect the interests” ofinvestors who traded during the relevant window. Rule23(a)(4). The requirement that the fraud-on-the-market
theory’s trade-timing predicate be established before
class certification thus sheds little light on the question
whether materiality must also be proved at the classcertification stage.
Amgen is not aided by Halliburton’s statement thatmarket efficiency and the public nature of the alleged
misrepresentations must be proved before a securitiesfraud class action can be certified. As Amgen notes, market efficiency, publicity, and materiality can all be proved
on a classwide basis. Furthermore, they are all essential
predicates of the fraud-on-the-market theory. Unless——————

Connecticut Retirement’s satisfaction of Rule 23(a)’s requirements.
8 Accordingly, “the timing of the relevant stock trades” is indeed an“element” of the fraud-on-the-market theory. Post, at 6, n. 6 (opinion of
THOMAS, J.). Unlike JUSTICE THOMAS, however, see ibid., we do notunderstand the United States as amicus curiae to take a different view.
See Brief for United States 15, n. 2 (“Precise identification of the times
when the alleged misrepresentation was made and the truth was
subsequently revealed is . . . important to ensure that the named
plaintiff has traded stock during the time the stock price allegedly was
distorted by the defendant’s misrepresentations.”).

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those predicates are established, there is no basis forpresuming that the defendant’s alleged misrepresentations were reflected in the security’s market price, andhence no grounding for any contention that investors
indirectly relied on those misrepresentations through theirreliance on the integrity of the market price. But unlike
materiality, market efficiency and publicity are not indispensable elements of a Rule 10b–5 claim. See Matrixx
Initiatives, 563 U. S., at ___ (slip op., at 9) (listing elements of a Rule 10b–5 claim). Thus, where the market fora security is inefficient or the defendant’s alleged misrepresentations were not aired publicly, a plaintiff cannot
invoke the fraud-on-the-market presumption. She can,however, attempt to establish reliance through the “traditional” mode of demonstrating that she was personally“aware of [the defendant’s] statement and engaged in a
relevant transaction . . . based on that specific misrepresentation.” Halliburton, 563 U. S., at ___ (slip op., at 4).
Individualized reliance issues would predominate in sucha lawsuit. See Basic, 485 U. S., at 242. The litigation,
therefore, could not be certified under Rule 23(b)(3) as aclass action, but the initiating plaintiff ’s claim would
remain live; it would not be “dead on arrival.” 660 F. 3d,
at 1175.
A failure of proof on the issue of materiality, in contrast,
not only precludes a plaintiff from invoking the fraud-onthe-market presumption of classwide reliance; it alsoestablishes as a matter of law that the plaintiff cannot
prevail on the merits of her Rule 10b–5 claim. Materiality
thus differs from the market-efficiency and publicity predicates in this critical respect: While the failure of common,classwide proof on the issues of market efficiency andpublicity leaves open the prospect of individualized proofof reliance, the failure of common proof on the issue ofmateriality ends the case for the class and for all individuals alleged to compose the class. See Brief for United

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States as Amicus Curiae 20 (“Unless the failure of common proof gives rise to a need for individualized proof, it
does not cast doubt on the propriety of class certification.”). In short, there can be no actionable reliance,
individually or collectively, on immaterial information. Because a failure of proof on the issue of materiality, unlike
the issues of market efficiency and publicity, does not giverise to any prospect of individual questions overwhelming
common ones, materiality need not be proved prior to Rule23(b)(3) class certification.
2
Amgen also contends that certain “policy considerations”
militate in favor of requiring precertification proof ofmateriality. Brief for Petitioners 28. An order grantingclass certification, Amgen observes, can exert substantial
pressure on a defendant “to settle rather than incur thecosts of defending a class action and run the risk of potentially ruinous liability.” Advisory Committee’s 1998 Noteon subd. (f) of Fed. Rule Civ. Proc. 23, 28 U. S. C. App.,p. 143. See also AT&T Mobility LLC v. Concepcion,
563 U. S. ___, ___ (2011) (slip op., at 16) (class actions
can entail a “risk of ‘in terrorem’ settlements”). Absent
a requirement to evaluate materiality at the classcertification stage, Amgen contends, the issue may neverbe addressed by a court, for the defendant will surrenderand settle soon after a class is certified. Insistence on
proof of materiality before certifying a securities-fraudclass action, Amgen thus urges, ensures that the issue
will be adjudicated and not forgone. See also post, at 4
(SCALIA, J., dissenting) (expressing the same concerns).
In this regard, however, materiality does not differ fromother essential elements of a Rule 10b–5 claim, notably,
the requirements that the statements or omissions on
which the plaintiff ’s claims are based were false or misleading and that the alleged statements or omissions

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caused the plaintiff to suffer economic loss. See Matrixx
Initiatives, 563 U. S., at ___ (slip op., at 9). Settlement
pressure exerted by class certification may prevent judicial resolution of these issues. Yet this Court has heldthat loss causation and the falsity or misleading nature of
the defendant’s alleged statements or omissions are common questions that need not be adjudicated before a classis certified. See Halliburton, 563 U. S., at ___ (slip op., at3) (loss causation need not be proved at the classcertification stage); Basic, 485 U. S., at 242 (“the falsity or
misleading nature of the . . . public statements” allegedly
made by the defendant is a “common questio[n]”). See also
Schleicher, 618 F. 3d, at 685 (falsity of alleged misstatements need not be proved before certification of asecurities-fraud class action).
Congress, we count it significant, has addressed thesettlement pressures associated with securities-fraud classactions through means other than requiring proof of materiality at the class-certification stage. In enacting thePrivate Securities Litigation Reform Act of 1995 (PSLRA),
109 Stat. 737, Congress recognized that although private
securities-fraud litigation furthers important public-policy
interests, prime among them, deterring wrongdoing andproviding restitution to defrauded investors, such lawsuits have also been subject to abuse, including the“extract[ion]” of “extortionate ‘settlements’ ” of frivolous
claims. H. R. Conf. Rep. No. 104–369, pp. 31–32 (1995).
The PSLRA’s response to the perceived abuses was, interalia, to “impos[e] heightened pleading requirements” forsecurities-fraud actions, “limit recoverable damages andattorney’s fees, provide a ‘safe harbor’ for forward-looking
statements, impose new restrictions on the selection of(and compensation awarded to) lead plaintiffs, mandate
imposition of sanctions for frivolous litigation, and authorize a stay of discovery pending resolution of any motion todismiss.” Merrill Lynch, Pierce, Fenner & Smith Inc. v.

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Dabit, 547 U. S. 71, 81–82 (2006). See also 15 U. S. C.
§78u–4 (2006 ed. and Supp. V). Congress later fortified
the PSLRA by enacting the Securities Litigation Uniform
Standards Act of 1998, 112 Stat. 3227, which curtailed
plaintiffs’ ability to evade the PSLRA’s limitations onfederal securities-fraud litigation by bringing class-action
suits under state rather than federal law. See 15 U. S. C.
§78bb(f)(1) (2006 ed.).
While taking these steps to curb abusive securitiesfraud lawsuits, Congress rejected calls to undo the fraudon-the-market presumption of classwide reliance endorsed
in Basic. See Langevoort, Basic at Twenty: Rethinking
Fraud on the Market, 2009 Wis. L. Rev. 151, 153, and n. 8
(noting that the initial version of H. R. 10, 104th Cong.,
1st Sess. (1995), an unenacted bill that, like the PSLRA,
was designed to curtail abuses in private securities litigation, “would have undone Basic”). See also Common Sense
Legal Reform Act: Hearings before the Subcommittee on
Telecommunications and Finance of the House Committee
on Commerce, 104th Cong., 1st Sess., 92, 236–237, 251–
252, 272 (1995) (witnesses criticized the fraud-on-themarket presumption and expressed support for H. R. 10’s
requirement that securities-fraud plaintiffs prove direct
reliance). Nor did Congress decree that securities-fraud
plaintiffs prove each element of their claim before obtaining class certification. Because Congress has homed in on
the precise policy concerns raised in Amgen’s brief, “[w]edo not think it appropriate for the judiciary to make its
own further adjustments by reinterpreting Rule 23 to
make likely success on the merits essential to class certification in securities-fraud suits.” Schleicher, 618 F. 3d, at
686; cf. Smith v. Bayer Corp., 564 U. S. ___, ___ (2011)(slip op., at 17–18) (“Congress’s decision to address therelitigation concerns associated with class actions throughthe mechanism of removal provides yet another reason forfederal courts to adhere in this context to longstanding

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principles of preclusion.”).
In addition to seeking our aid in warding off “in terrorem” settlements, Amgen also argues that requiring
proof of materiality before class certification would conserve judicial resources by sparing judges the task ofoverseeing large class proceedings in which the essential
element of reliance cannot be proved on a classwide basis.
In reality, however, it is Amgen’s position, not the judgments of the lower courts in this case, that would waste
judicial resources. Amgen’s argument, if embraced, would
necessitate a mini-trial on the issue of materiality at theclass-certification stage. Such preliminary adjudications
would entail considerable expenditures of judicial timeand resources, costs scarcely anticipated by Federal Ruleof Civil Procedure 23(c)(1)(A), which instructs that thedecision whether to certify a class action be made “[a]t an
early practicable time.” If the class is certified, materiality
might have to be shown all over again at trial. And if
certification is denied for failure to prove materiality,
nonnamed class members would not be bound by that
determination. See Smith, 564 U. S., at ___ (slip op.,at 12–18). They would be free to renew the fray, perhaps
in another forum, perhaps with a stronger showing ofmateriality.
Given the tenuousness of Amgen’s judicial-economy
argument, Amgen’s policy arguments ultimately return tothe contention that private securities-fraud actions shouldbe hemmed in to mitigate their potentially “vexatiou[s]”character. Blue Chip Stamps v. Manor Drug Stores, 421
U. S. 723, 739 (1975). We have already noted what Congress has done to control exorbitant securities-fraud actions. See supra, at 19–20. Congress, the Executive
Branch, and this Court, moreover, have “recognized thatmeritorious private actions to enforce federal antifraud
securities laws are an essential supplement to criminal
prosecutions and civil enforcement actions brought, re-

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spectively, by the Department of Justice and the Securities and Exchange Commission.” Tellabs, Inc. v. Makor
Issues & Rights, Ltd., 551 U. S. 308, 313 (2007); see H. R.
Conf. Rep. No. 104–369, at 31; Brief for United States as
Amicus Curiae 1. See also Amchem, 521 U. S., at 617(“ ‘The policy at the very core of the class action mechanism is to overcome the problem that small recoveries do
not provide the incentive for any individual to bring a solo
action prosecuting his or her rights.’ ” (quoting Mace v.
Van Ru Credit Corp., 109 F. 3d 338, 344 (CA7 1997))). We
have no warrant to encumber securities-fraud litigation
by adopting an atextual requirement of precertification
proof of materiality that Congress, despite its extensive involvement in the securities field, has not sanctioned.
C
JUSTICE SCALIA acknowledges that proof of materiality
is not required to satisfy Rule 23(b)(3)’s predominancerequirement. See post, at 1. Nevertheless, he maintains
that full satisfaction of Rule 23’s requirements is insufficient to obtain class certification under Basic. In JUSTICESCALIA’s view, the Court’s decision in Basic established a
special rule: A securities-fraud class action cannot becertified unless all of the prerequisites of the fraud-on-themarket presumption of reliance, including materiality,
have first been established. Post, at 2.
The purported rule is JUSTICE SCALIA’s invention. It
cannot be attributed to anything the Court said in Basic.
That decision is best known for its endorsement of thefraud-on-the-market theory. But the opinion also established something more. It stated the proper standard for
judging the materiality of misleading statements regarding the existence and status of preliminary merger discussions. See 485 U. S., at 230–241, 250 (“Materiality in themerger context depends on the probability that the transaction will be consummated, and its significance to the96

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issuer of the securities.”). The District Court in Basiccertified a class of investors whose share prices were
allegedly depressed by misleading statements that disguised ongoing merger negotiations. Id., at 228. Postcertification, the court granted summary judgment to thedefendants on the ground that the alleged misstatements
were immaterial as a matter of law. Id., at 228–229. The
Court of Appeals affirmed the class certification but reversed the grant of summary judgment. Id., at 229. This
Court, in turn, vacated the Court of Appeals’ judgment
and remanded for further proceedings on the defendants’summary-judgment motion in light of the materiality
standard set forth in the Court’s opinion. Id., at 240–241,250. Notably, however, we did not disturb the District
Court’s class-certification order, which we stated “wasappropriate when made.” Id., at 250.9
If JUSTICE SCALIA were correct that our decision in
Basic demands proof of materiality before class certification, the Court in Basic should have ordered the lower
courts to reconsider on remand both the defendants’ entitlement to summary judgment and the propriety of classcertification. Instead, the Court expressly endorsed theDistrict Court’s class-certification order while at the sametime recognizing that further proceedings were necessary
to determine whether the plaintiffs had mustered sufficient evidence to satisfy the relatively lenient standard for——————
9 Scouring the Court’s decision in Basic for some semblance of support
for his position, JUSTICE SCALIA attaches portentous significance to
Basic’s statement that the District Court’s class-certification order,
although “ ‘appropriate when made,’ ” was “ ‘subject on remand to suchadjustment, if any, as developing circumstances demand[ed].’ ” Post, at
2 (quoting Basic, 485 U. S., at 250). This statement, however, merely
reminds that certifications are not frozen once made. Rule 23 empowers district courts to “alte[r] or amen[d]” class-certification orders basedon circumstances developing as the case unfolds. Fed. Rule Civ. Proc.
23(c)(1) (1988). See also Rule 23(c)(1)(C) (2013).

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avoiding summary judgment. See Anderson v. Liberty
Lobby, Inc., 477 U. S. 242, 248 (1986) (“[S]ummary judgment will not lie if . . . the evidence is such that a reasonable jury could return a verdict for the nonmoving party.”).
Unlike JUSTICE SCALIA, we are unwilling to presume that
Basic announced a rule requiring precertification proof ofmateriality when Basic failed to apply any such rule to thevery case before it.10
III
Amgen also argues that the District Court erred byrefusing to consider the rebuttal evidence Amgen profferedin opposing Connecticut Retirement’s class-certification
motion. This evidence, Amgen contends, showed that “inlight of all the information available to the market,” its
alleged misrepresentations and misleading omissions“could not be presumed to have altered the market pricebecause they would not have ‘significantly altered thetotal mix of information made available.’ ” Brief for Petitioners 40–41 (quoting Basic, 485 U. S., at 232). For example, Connecticut Retirement’s complaint alleges that an
Amgen executive misleadingly downplayed the significance of an upcoming Food and Drug Administration
advisory committee meeting by incorrectly stating that themeeting would not focus on one of Amgen’s leading drugs.
See App. to Pet. for Cert. 17a. Amgen responded to thisallegation by presenting public documents—including thecommittee’s meeting agenda, which was published in the——————
10 JUSTICE SCALIA suggests that the Court’s approach in Basic might

have been influenced by the obsolete view that “ ‘Rule 23 . . . set[s] fortha mere pleading standard.’ ” Post, at 3 (quoting Wal-Mart Stores, Inc. v.
Dukes, 564 U. S. ___, ___ (2011) (slip op., at 10)). The opinion in Basic,
however, provides no indication that the Court perceived any issue
before it to turn on the question whether a plaintiff must merely plead,rather than “affirmatively demonstrate,” her satisfaction of Rule 23’s
certification requirements. Dukes, 564 U. S., at ___ (slip op., at 10).

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Federal Register more than a month before the meeting—stating that safety concerns associated with Amgen’s drug
would be discussed at the meeting. See id., at 41a–42a.
See also 69 Fed. Reg. 16582 (2004).
The District Court did not err, we agree with the Courtof Appeals, by disregarding Amgen’s rebuttal evidence indeciding whether Connecticut Retirement’s proposed classsatisfied Rule 23(b)(3)’s predominance requirement. The
Court of Appeals concluded, and Amgen does not contest,
that Amgen’s rebuttal evidence aimed to prove that themisrepresentations and omissions alleged in Connecticut
Retirement’s complaint were immaterial.
660 F. 3d,
at 1177 (characterizing Amgen’s rebuttal evidence as
an attempt to present a “ ‘truth-on-the-market’ defense,”
which the Court of Appeals explained “is a method of
refuting an alleged misrepresentation’s materiality”). See
also Reply Brief 17 (Amgen’s evidence was offered to rebut
the “materiality predicate” of the fraud-on-the-market
theory). As explained above, however, the potential immateriality of Amgen’s alleged misrepresentations andomissions is no barrier to finding that common questions
predominate. See Part II, supra. If the alleged misrepresentations and omissions are ultimately found immaterial,
the fraud-on-the-market presumption of classwide reliancewill collapse. But again, as earlier explained, see supra, at
10–13, individual reliance questions will not overwhelm
questions common to the class, for the class members’
claims will have failed on their merits, thus bringing thelitigation to a close. Therefore, just as a plaintiff class’s
inability to prove materiality creates no risk that individual questions will predominate, so even a definitive rebuttal on the issue of materiality would not undermine thepredominance of questions common to the class.
We recognized as much in Basic itself. A defendant
could “rebut the [fraud-on-the-market] presumption ofreliance,” we observed in Basic, by demonstrating that“news of the [truth] credibly entered the market and dissi-

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Opinion of the Court

pated the effects of [prior] misstatements.” 485 U. S., at248–249. We emphasized, however, that “[p]roof of thatsort is a matter for trial” (and presumably also for a summary-judgment motion under Federal Rule of Civil Procedure 56). Id., at 249, n. 29.11 The District Court thus
correctly reserved consideration of Amgen’s rebuttal evidence for summary judgment or trial. It was not required
to consider the evidence in determining whether common
questions predominated under Rule 23(b)(3).
***
For the reasons stated, the judgment of the Court ofAppeals for the Ninth Circuit is affirmed.
It is so ordered.

——————
11 Amgen attempts to minimize the import of this statement by notingthat it was made prior to a 2003 amendment to Rule 23 that eliminateddistrict courts’ authority to conditionally certify class actions. See
Advisory Committee’s 2003 Note on subd. (c)(1) of Fed. Rule Civ.
Proc. 23, 28 U. S. C. App., p. 144. Nothing in our opinion in Basic,
however, suggests that the statement relied in any way on district
courts’ conditional-certification authority. To the contrary, the Court in
Basic stated: “Proof of that sort [i.e., that news of the truth had entered
the market and dissipated the effects of prior misstatements] is amatter for trial, throughout which the District Court retains theauthority to amend the certification order as may be appropriate.” 485
U. S., at 249, n. 29 (emphasis added). Rule 23(c)(1)(C) continues toprovide that a class-certification order “may be altered or amended
before final judgment.”100

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1

ALITO, J., concurring

SUPREME COURT OF THE UNITED STATES_________________

No. 11–1085_________________AMGEN INC., ET AL., PETITIONERS v. CONNECTICUTRETIREMENT PLANS AND TRUST FUNDSON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF
APPEALS FOR THE NINTH CIRCUIT[February 27, 2013]JUSTICE ALITO, concurring.
I join the opinion of the Court with the understandingthat the petitioners did not ask us to revisit Basic’s fraudon-the-market presumption. See Basic Inc. v. Levinson,
485 U. S. 224 (1988). As the dissent observes, more recent evidence suggests that the presumption may rest on
a faulty economic premise. Post, at 4, n. 4 (opinion of
THOMAS, J.); see Langevoort, Basic at Twenty: Rethinking
Fraud on the Market, 2009 Wis. L. Rev. 151, 175–176. In
light of this development, reconsideration of the Basicpresumption may be appropriate.

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SCALIA, J., dissenting

SUPREME COURT OF THE UNITED STATES_________________

No. 11–1085_________________AMGEN INC., ET AL., PETITIONERS v. CONNECTICUTRETIREMENT PLANS AND TRUST FUNDSON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF
APPEALS FOR THE NINTH CIRCUIT[February 27, 2013]JUSTICE SCALIA, dissenting.
I join the principal dissent, that of JUSTICE THOMAS,
except for Part I–B.
The fraud-on-the-market rule says that purchase orsale of a security in a well functioning market establishes
reliance on a material misrepresentation known to themarket. This rule is to be found nowhere in the UnitedStates Code or in the common law of fraud or deception; it
was invented by the Court in Basic Inc. v. Levinson, 485
U. S. 224 (1988). Today’s Court applies to that rule theprinciples of Federal Rule of Civil Procedure 23(b)(3), andthereby concludes (logically enough) that commonality isestablished at the certification stage even when materiality has not been shown. That would be a correct procedure
if Basic meant the rule it announced to govern only thequestion of substantive liability—what must be shown inorder to prevail. If that were so, the new substantive rule,
like the more general substantive rule that reliance must
be proved, would be subject, at the certification stage, tothe commonality analysis of Rule 23(b)(3). In my view,
however, the Basic rule of fraud-on-the-market—a wellfunctioning market plus purchase or sale in the market
plus material misrepresentation known to the market
establishes a necessary showing of reliance—governs not
only the question of substantive liability, but also the

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question whether certification is proper. All of the elements of that rule, including materiality, must be established if and when it is relied upon to justify certification.
The answer to the question before us today is to be found
not in Rule 23(b)(3), but in the opinion of Basic.
Basic established a presumption that the misrepresentation was relied upon, not a mere presumption that theplaintiffs relied on the market price. And it establishedthat presumption not just for the question of substantive
liability but also for the question of certification. “Wegranted certiorari . . . to determine whether the courts
below properly applied a presumption of reliance in certifying the class, rather than requiring each class member toshow direct reliance on Basic’s statements.” 485 U. S., at
230 (emphasis added). Of course it makes no sense to“presume reliance” on the misrepresentation merely because the plaintiff relied on the market price, unless thealleged misrepresentation would likely have affected themarket price—that is, unless it was material. Thus, as
JUSTICE THOMAS’ dissent shows, the Basic opinion is shot
through with references to the necessary materiality. The
presumption of reliance does not apply, and hence neither
substantive liability will attach nor will certification beproper, unless materiality is shown. The necessity ofmateriality for certification is demonstrated by the lastsentence of the Basic opinion, which comes after the Court
has decided to remand the case for reconsideration ofmateriality under the appropriate legal standard: “TheDistrict Court’s certification of the class here was appropriate when made but is subject on remand to such adjustment, if any, as developing circumstances demand.”Id., at 250. Those circumstances are the establishment offacts that rebut the presumption, including of facts thatshow the misrepresentation was not material, or was notknown to the market.
The Court argues that if materiality were a predicate to103

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certification on a fraud-on-the-market theory, the Basic
Court would not have approved the class certification
order while remanding for reconsideration of “whether
the plaintiffs had mustered sufficient evidence to satisfy
the relatively lenient standard for avoiding summary judgment.” See ante, at 23–24. The Court manufactures aninconsistency on the basis of doctrine that did not govern
class certification at the time of Basic. We recently clarified that “Rule 23 does not set forth a mere pleading
standard.” Wal-Mart Stores, Inc. v. Dukes, 564 U. S. ___,___ (2011) (slip op., at 10). But review of the Basic certification order shows that the District Court’s fraud-on-themarket analysis was based exclusively on the pleadings:“[T]he allegations of plaintiffs’ complaint are sufficient tobring this section 10(b) and Rule 10(b)(5) claim within theso-called ‘fraud on the market’ theory.” App. to Pet. for
Cert. in Basic Inc. v. Levinson, O. T. 1987, No. 86–279,
p. 115a (emphasis added); see also ibid. (citing complaint
paragraphs as establishing fraud on the market). Under apleadings standard, the District Court found that theplaintiffs had satisfied Rule 23(b)(3) with regard to fraudon the market, including its materiality predicate. See id.,
at 133a (denial of reconsideration) (“This court ruled on
December 10 that transaction causation [i.e., reliance]
could be established by the following: proof of a material
misrepresentation which affected the market price of thestocks with a resulting injury to the plaintiffs” (emphasis
added)). Thus, even if the plaintiffs sufficiently pleaded
materiality that the certification order “was appropriate
when made,” Basic, supra, at 250, the defendants retained
an opportunity on remand to rebut the pleading in order todefeat certification.*——————* As for the Court’s contention that I have “[s]cour[ed] the Court’s
decision in Basic” to find “some semblance of support” for my reading of
the case, ante, at 23, n. 9: It does not take much scouring to come across

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Certification of the class is often, if not usually, theprelude to a substantial settlement by the defendantbecause the costs and risks of litigating further are sohigh. It does an injustice to the Basic Court to presume
without clear evidence—and indeed in the face of language
to the contrary—that it was establishing a regime inwhich not only those market class-action suits that haveearned the presumption of reliance pass beyond the crucial certification stage, but all market-purchase andmarket-sale class-action suits do so, no matter what the alleged misrepresentation. The opinion need not be readthis way, and it should not.
The fraud-on-the-market theory approved by Basic envisions a demonstration of materiality not just for substantive recovery but for certification. Today’s holding
does not merely accept what some consider the regrettableconsequences of the four-Justice opinion in Basic; it expands those consequences from the arguably regrettable tothe unquestionably disastrous.

——————
the Court’s opening statement that “[w]e granted certiorari . . . todetermine whether the courts below properly applied a presumption ofreliance in certifying the class.” 485 U. S., at 230 (emphasis added).

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1

THOMAS, J., dissenting

SUPREME COURT OF THE UNITED STATES_________________

No. 11–1085_________________AMGEN INC., ET AL., PETITIONERS v. CONNECTICUTRETIREMENT PLANS AND TRUST FUNDSON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF
APPEALS FOR THE NINTH CIRCUIT[February 27, 2013]JUSTICE THOMAS, with whom JUSTICE KENNEDY joins,
and with whom JUSTICE SCALIA joins except for Part I–B,
dissenting.
I
The Court today allows plaintiffs to obtain certificationof securities-fraud class actions without proof that common questions predominate over individualized questionsof reliance, in contravention of Federal Rule of Civil Procedure 23(b)(3). The Court does so by all but eliminating
materiality as one of the predicates of the fraud-on-themarket theory, which serves as an alternative mode of establishing reliance. See Basic Inc. v. Levinson, 485 U. S.
224, 241–250 (1988). Without demonstrating materiality
at certification, plaintiffs cannot establish Basic’s fraudon-the-market presumption. Without proof of fraud on themarket, plaintiffs cannot show that otherwise individualized questions of reliance will predominate, as requiredby Rule 23(b)(3). And without satisfying Rule 23(b)(3),class certification is improper. Fraud on the market isthus a condition precedent to class certification, without
which individualized questions of reliance will defeat
certification.
The Court’s opinion depends on the following assumption: Plaintiffs will either (1) establish materiality at themerits stage, in which case class certification was proper

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because reliance turned out to be a common question, or(2) fail to establish materiality, in which case the claim
would fail on the merits, notwithstanding the fact thatthe class should not have been certified in the first place,because reliance was never a common question. The
failure to establish materiality retrospectively confirmsthat fraud on the market was never established, thatquestions regarding the element of reliance were notcommon under Rule 23(b)(3), and, by extension, thatcertification was never proper. Plaintiffs cannot be excused of their Rule 23 burden to show at certification thatquestions of reliance are common merely because theymight lose later on the merits element of materiality.
Because a securities-fraud plaintiff invoking Basic’s fraudon-the-market presumption to satisfy Rule 23(b)(3) should
be required to prove each of the predicates of that theory
at certification in order to demonstrate that questions ofreliance are common to the class, I respectfully dissent.
A
We begin with §10 of the Securities Exchange Act of1934, 15 U. S. C. §78j (2006 ed. and Supp. V).1 We “haveimplied a private cause of action from the text and purposes of §10(b)” and Securities and Exchange Commission
Rule 10b–5, 17 CFR §240.10b–5 (2011).2 Matrixx Initia——————

1 Section 10 states, in relevant part:“It shall be unlawful for any person, directly or indirectly, by the useof any means or instrumentality of interstate commerce or of the mails,
or of any facility of any national securities exchange—
.
.
.
.
.
“(b) To use or employ, in connection with the purchase or sale of any
security registered on a national securities exchange . . . any manipulative or deceptive device or contrivance in contravention of such rules
and regulations as the Commission may prescribe . . . .”2 Rule 10b–5 states:“It shall be unlawful for any person, directly or indirectly, by the useof any means or instrumentality of interstate commerce, or of the mails

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tives, Inc. v. Siracusano, 563 U. S. ___, ___ (2011) (slip op.,at 9). See also Superintendent of Ins. of N. Y. v. Bankers
Life & Casualty Co., 404 U. S. 6, 13, n. 9 (1971) (“It is now
established that a private right of action is implied under§10(b)”). The elements of an implied §10(b) cause of action
for securities fraud are “ ‘(1) a material misrepresentationor omission by the defendant; (2) scienter; (3) a connection
between the misrepresentation or omission and the purchase or sale of a security; (4) reliance upon the misrepresentation or omission; (5) economic loss; and (6) losscausation.’ ” Matrixx, supra, at ___ (slip op., at 9) (quoting
Stoneridge Investment Partners, LLC v. Scientific-Atlanta,
Inc., 552 U. S. 148, 157 (2008)). This case concerns thereliance element of the §10(b) claim and its interaction
with Rule 23(b)(3).
To prove reliance, a plaintiff, whether proceeding individually or as a class member, must show that his stocktransaction was caused by the specific alleged misstatement. “[P]roof of reliance ensures that there is a proper‘connection between a defendant’s misrepresentation anda plaintiff ’s injury.’ ” Erica P. John Fund, Inc. v. Halliburton Co., 563 U. S. ___, ___ (2011) (slip op., at 4)(quoting Basic, supra, at 243).3 To satisfy this element, a——————or of any facility of any national securities exchange,“(a) To employ any device, scheme, or artifice to defraud,“(b) To make any untrue statement of a material fact or to omit tostate a material fact necessary in order to make the statements made,in the light of the circumstances under which they were made, notmisleading, or“(c) To engage in any act, practice, or course of business which
operates or would operate as a fraud or deceit upon any person, in
connection with the purchase or sale of any security.”
3 Courts have also “referred to the element of reliance as ‘transaction
causation.’ ” Erica P. John Fund, 563 U. S., at ___ (slip op., at 6)(quoting Dura Pharmaceuticals, Inc. v. Broudo, 544 U. S. 336, 341–342(2005), in turn citing Basic Inc. v. Levinson, 485 U. S. 224, 248–249(1988)). This alternative phrasing recognizes that the reliance inquiry

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plaintiff traditionally was required to “sho[w] that he wasaware of a company’s statement and engaged in a relevanttransaction . . . based on that specific misrepresentation.”
Erica P. John Fund, supra, at ___ (slip op., at 4) (emphasis
added). In the face-to-face fraud cases from which securities claims historically arose, see, e.g., Dura Pharmaceuticals, Inc. v. Broudo, 544 U. S. 336, 343–344 (2005)(discussing common-law roots of securities-fraud actions),
this requirement was easily met by showing that the seller
made statements directly to the purchaser and that thepurchaser bought stock in reliance on those statements.
However, in a modern securities market many, if not most,individuals who purchase stock from third parties on animpersonal exchange will be unaware of statements madeby the issuer of those securities. As a result, such purchaser-plaintiffs are unable to meet the traditional reliance requirement because they cannot establish that they
“engaged in a relevant transaction . . . based on [a] specificmisrepresentation.” Erica P. John Fund, supra, at ___(slip op., at 4).
This concern was the driving force behind the development of the fraud-on-the-market theory adopted in Basic.
Because individuals trading stock on an impersonal market often cannot show reliance even for purposes of anindividual securities-fraud action, Basic permitted “plaintiffs to invoke a rebuttable presumption of reliance.” Erica
P. John Fund, supra, at ___ (slip op., at 5).4 Basic pre——————

is directed at determining whether a particular piece of information
caused an individual to enter into a given transaction.
4 The Basic decision itself is questionable. Only four Justices joined
the portion of the opinion adopting the fraud-on-the-market theory.
Justice White, joined by Justice O’Connor, dissented from that section,emphasizing that “[c]onfusion and contradiction in court rulings areinevitable when traditional legal analysis is replaced with economic
theorization by the federal courts” and that the Court is “not wellequipped to embrace novel constructions of a statute based on contemporary microeconomic theory.” 485 U. S., at 252–253 (concurring in

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THOMAS, J., dissenting

sumes that “ ‘in an open and developed securities market,
the price of a company’s stock is determined by the available material information regarding the company and its
business.’ ” 485 U. S., at 241 (quoting Peil v. Speiser, 806
F. 2d 1154, 1160–1161 (CA3 1986); emphasis added).5“ ‘Misleading statements will therefore defraud purchasersof stock even if the purchasers do not directly rely on the
misstatements.’ ” 485 U. S., at 241–242. As a result, “[a]ninvestor who buys or sells stock at the price set by themarket does so in reliance on the integrity of that price,”and “an investor’s reliance on any public material misrepresentations” may therefore “be presumed for purposes of aRule 10b–5 action.” Id., at 247 (emphasis added).
If a plaintiff opts to show reliance through fraud on themarket, Basic is clear that the plaintiff must show thefollowing predicates in order to prevail: (1) an efficient
market, (2) a public statement, (3) that the stock wastraded after the statement was made but before the truth——————

part and dissenting in part). Justice White’s concerns remain valid
today, but the Court has not been asked to revisit Basic’s fraud-on-themarket presumption. I thus limit my dissent to demonstrating that the
Court is not following Basic’s dictates.
Moreover, the Court acknowledges there is disagreement as towhether market efficiency is “ ‘ “a binary, yes or no question,” ’ ” or instead operates differently depending on the information at issue, seeante, at 14, n. 6 (quoting Brief for Petitioners 32, in turn quoting
Langevoort, Basic at Twenty: Rethinking Fraud on the Market, 2009
Wis. L. Rev. 151, 167).
5 Basic “adopt[ed] the TSC Industries standard of materiality for the§10(b) and Rule 10b–5 context.” 485 U. S., at 232. That standard
indicates that “ ‘[a]n omitted fact is material if there is a substantial
likelihood that a reasonable shareholder would consider it important indeciding how to vote.’ ” Id., at 231 (quoting TSC Industries, Inc. v.
Northway, Inc., 426 U. S. 438, 449 (1976); alteration in original). “[T]ofulfill the materiality requirement ‘there must be a substantial likelihood that the disclosure of the omitted fact would have been viewed by
the reasonable investor as having significantly altered the “total mix” ofinformation made available.’ ” 485 U. S., at 231–232 (quoting TSC
Industries, supra, at 449).

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was revealed, and (4) the materiality of the statement.
Id., at 248, n. 27.6 Both the Court and respondent agree
that materiality is a necessary component of fraud on themarket. See, e.g., ante, at 9 (materiality is “indisputably”“an essential predicate of the fraud-on-the-market theory”); Brief for Respondent 29 (“If the statement is notmaterially false, then no one in the class can establish
reliance via the integrity of the market”). The materialityof a specific statement is, therefore, essential to the fraudon-the-market presumption, which in turn enables aplaintiff to prove reliance.
B
Basic’s fraud-on-the-market presumption is highly sig——————
6 The United States as amicus curiae invokes Rule 23(a)(3) to suggestthat the third element, the timing of the relevant stock trades, is a“limit on the definition of the class.” Brief for United States 15, n. 2.
But it is also necessary to establish the timing of the allegedly material,
public misstatement made into an allegedly efficient market (as well as
when the fraud ended due to entry of truth on the market) before thefraud-on-the-market theory can be evaluated under Rule 23(b)(3).
Thus, the lower court opinion in Basic expressly identified “the time themisrepresentations were made and the time the truth was revealed” aspart of fraud on the market. Levinson v. Basic Inc., 786 F. 2d 741, 750(CA6 1986). The Basic Court cited the formulation approvingly, 485
U. S., at 248, n. 27, and recently in Erica P. John Fund, Inc. v. Halliburton Co., 563 U. S. ___ (2011), the Court cited the same language aspart of the “undisputed” elements a securities-fraud plaintiff must
prove to invoke Basic. 563 U. S., at ___ (slip op., at 5–6) (quoting Basic,supra, at 248, n. 27). Unless the timing of the misrepresentation andtruth is established at certification, there is no framework within which
to determine whether fraud on the market renders reliance a common
question. Thus, insofar as the majority recognizes that timing is afactor of the fraud-on-the-market theory, ante, at 16, n. 8, I agree. It
would be incorrect to suggest that timing solely relates to Rules 23(a)(3)and (4). It is equally important to establish the timing range at certification for Rule 23(b)(3) reliance purposes. This fact undercuts the
majority’s attempt to isolate materiality as the only factor of fraud on
the market that need not be shown at certification to demonstrate that
reliance is a common question.

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nificant because it makes securities-fraud class actions
possible by converting the inherently individual relianceinquiry into a question common to the class, which isnecessary to satisfy the dictates of Rule 23(b)(3).7 Rule23(b)(3) requires the party seeking certification to provethat “questions of law or fact common to class members
predominate over any questions affecting only individual
members.” A plaintiff seeking class certification is not
required to prove the elements of his claim at the certification stage, but he must show that the elements of theclaim are susceptible to classwide proof. See, e.g., WalMart Stores, Inc. v. Dukes, 564 U. S. ___, ___, n. 6 (2011)(slip op., at 11, n. 6) (“[P]laintiffs seeking 23(b)(3) certification must prove that their shares were traded on an efficient market,” an element of the fraud-on-the-market
theory (emphasis added)). Without that proof, there isno justification for certifying a class because there is no“ ‘capacity of a classwide proceeding to generate common
answers apt to drive the resolution of the litigation.’ ” Id.,
at ___ (slip op., at 9–10) (quoting Nagareda, Class Certification in the Age of Aggregate Proof, 84 N. Y. U. L. Rev.
97, 132 (2009)).
If plaintiffs fail to show that reliance is a common question at the time of certification, certification is improper.
For if reliance is not a common question, each plaintiff
would be required to prove that he in fact relied on a
misstatement, a showing which is simply not susceptible
to classwide proof. Individuals make stock transactions
for divergent, even idiosyncratic, reasons. As the leading
pre-Basic fraud-on-the-market case recognized, “[a] purchaser on the stock exchanges may be either unaware of a
specific false representation, or may not directly rely on it;
he may purchase because of a favorable price trend, price——————
7 There is no dispute that respondent meets the prerequisites of Fed.
Rule Civ. Proc. 23(a).

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earnings ratio, or some other factor.” Blackie v. Barrack,
524 F. 2d 891, 907 (CA9 1975). The inquiry’s inherently
individualized nature renders it impossible to generate thecommon answers necessary for certification under Rule23(b)(3). See Basic, 485 U. S., at 242 (“Requiring proof ofindividualized reliance from each member of the proposed
plaintiff class effectively would have prevented respondents from proceeding with a class action, since individual
issues then would have overwhelmed the common ones”).
The Court’s solution in Basic was to allow putative classmembers to prove reliance through the fraud-on-themarket presumption. Id., at 241–250. As the Court today
recognizes, failure to establish fraud on the market “leaves
open the prospect of individualized proof of reliance.”
Ante, at 17. Notably, the Court and the Ninth Circuit both
acknowledge that in order to obtain the benefit of thepresumption, plaintiffs must establish two of the fraud-onthe-market predicates at class certification: (1) that themarket was generally efficient, and (2) that the alleged
misstatement was public. See ante, at 16 (acknowledging“that market efficiency and the public nature of the alleged
misrepresentations must be proved before a securitiesfraud class action can be certified”); 660 F. 3d 1170, 1175
(CA9 2011) (same). See also Erica P. John Fund, 563
U. S., at ___ (slip op., at 5) (“It is undisputed that
securities fraud plaintiffs must prove,” at certificationinter alia, “that the alleged misrepresentations were publicly known . . . [and] that the stock traded in an efficient
market”). The Court is correct insofar as its statements
recognize that fraud on the market is a condition precedent to showing that there are common questions of reliance at the time of class certification.
Nevertheless, the Court asserts that materiality—by its
own admission an essential predicate to invoking fraudon the market—need not be established at certification
because it will ultimately be proved at the merits stage.

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Ante, at 16–18. This assertion is an express admissionthat parties will not know at certification whether relianceis an individual or common question.
To support its position, the Court transforms the predicate certification inquiry into a novel either-or inquiry
occurring much later on the merits. According to the
Court, either (1) plaintiffs will prove materiality on the
merits, thus demonstrating ex post that common questions
predominated at certification, or (2) they will fail to provemateriality, at which point we learn ex post that certification was inappropriate because reliance was not, in fact, acommon question. In the Court’s second scenario, fraudon the market was never established, reliance for eachclass member was inherently individualized, and Rule23(b)(3) in fact should have barred certification long ago.8
The Court suggests that the problem created by the second
scenario is excusable because the plaintiffs will lose anyway on alternative merits grounds, and the case will be——————
8 The majority ignores this explanation of the fundamental flaw in
its position, asserting that I never “explain how . . . a plaintiff class’s
failure to prove an essential element of its claim for relief will result in
individual questions predominating over common ones.” Ante, at 12.
But a plaintiff, who is excused from his burden of showing, at certification that reliance is a common question, fails to demonstrate that
common questions predominate over the individualized questions of reliance that are inherent in a securities fraud claim. A plaintiff mustcarry this burden at certification for certification to be proper. The
majority does not respond to the inherent timing problem in its position. It does not explain how ignoring questions of reliance—that
undeniably will be individualized in some cases—at certification isjustified by the fact that those questions will be resolved months or
years later on the merits in a way that indicates reliance was indeed an
individualized question all along. Far from obeying the dictates of Rule23(b)(3) as it claims, ante, at 12–13, the majority unjustifiably puts off acritical part of the Rule 23(b)(3) inquiry until the merits. The only way
the majority can purport to follow Rule 23(b)(3) is by ignoring the fact
that, under its own analysis, reliance may be an individualized question that predominates over common questions at certification.

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over. See ante, at 17 (“[F]ailure of proof on the issue ofmateriality [at the merits stage] . . . not only precludes aplaintiff from invoking the fraud-on-the-market presumption of classwide reliance; it also establishes as a matter oflaw that the plaintiff cannot prevail on the merits of her
Rule 10b–5 claim”). But nothing in logic or precedentjustifies ignoring at certification whether reliance is susceptible to Rule 23(b)(3) classwide proof simply because
one predicate of reliance—materiality—will be resolved, if
at all, much later in the litigation on an independent
merits element.
It is the Court, not Amgen, that “would have us put the
cart before the horse,” ante, at 3, by jumping chronologically to the §10(b) merits element of materiality. But Rule23, as well as common sense, requires class certification
issues to be addressed first. See Rule 23(c)(1)(A) (“At an
early practicable time after a person sues or is sued . . .
the court must determine by order whether to certify theaction as a class action”). A plaintiff who cannot provemateriality does not simply have a claim that is “ ‘dead on
arrival’ ” at the merits, ante, at 17 (quoting 660 F. 3d, at1175); he has a class that should never have arrived at themerits at all because it failed Rule 23(b)(3) certificationfrom the outset. Without materiality, there is no fraudon-the-market presumption, questions of reliance remain
individualized, and Rule 23(b)(3) certification is impossible. And the fact that evidence of materiality goes to bothfraud on the market at certification and an independent
merits element is no issue; Wal-Mart expressly held that a
court at certification may inquire into questions that also
have later relevance on the merits. See 564 U. S., at ___(slip op., at 10–11). The Court reverses that inquiry,
effectively saying that certification may be put off until
later because an adverse merits determination will retroactively wipe out the entire class. However, a plaintiff
who cannot prove materiality cannot prove fraud on the115

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market and, thus, cannot demonstrate that the question ofreliance is susceptible of a classwide answer.
The fact that a statement may prove to be material at
the merits stage does not justify conflating the doctrinallyindependent (and distinct) elements of materiality andreliance.9 The Court’s error occurs when, instead of asking whether the element of reliance is susceptible toclasswide proof, the Court focuses on whether materiality
is susceptible to classwide proof. Ante, at 10 (“[T]he pivotal inquiry is whether proof of materiality is needed toensure that the questions of law or fact common to theclass will ‘predominate’ ”). The result is that the Court
effectively equates §10(b) materiality with fraud-on-themarket materiality and elides reliance as a §10(b) element. But a plaintiff seeking certification under Rule 23
bears the burden of proof with regard to all the elementsof a §10(b) claim, which includes materiality and reliance.
As Wal-Mart explained, “[a] party seeking class certification must affirmatively demonstrate his compliance with——————
9 Of course, the Court’s assertion that materiality will be resolved on
the merits presumes that certification will not bring in terrorem settlement pressures to bear, foreclosing any materiality inquiry at all. The
Court dismisses this concern, ante, at 18–20, attempting to give fraudon-the-market analysis the imprimatur of congressional enactment
instead of recognizing it as a judicially created doctrine grafted onto an
implied cause of action. But the fact that Congress has enacted legislation to curb excesses in securities litigation while leaving Basic intact,
see ante, at 19–20, says nothing about the proper interpretation of
Basic at issue here. The Court retains discretion over the contours of
Basic unless and until Congress sees fit to alter them—a fact Congress
must also have realized when it passed the Private Securities Litigation Reform Act of 1995, 109 Stat. 737, and other legislation. The
Court’s entire argument is based on the assumption that the fraud-onthe-market presumption need not be shown at certification because it
will be proved later on the merits; insofar as certification makes thatlater determination unlikely to occur, it at least counsels against thecertitude with which the Court assures us that its gloss on Basic iscorrect.

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AND TRUST FUNDS
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the Rule—that is, he must be prepared to prove that there
are in fact sufficiently numerous parties, common questions of law or fact, etc.” 564 U. S., at ___ (slip op., at 10).
If the elements of fraud on the market are not proved atcertification, a plaintiff has failed to carry his burden of
establishing that questions of individualized reliance will
not predominate, without which the plaintiff class cannot
obtain certification. Cf. id., at ___ (slip op., at 12) (holdingin Rule 23(a)(2) context that “[w]ithout some glue holding the alleged reasons for all those decisions together, it
will be impossible to say that examination of all the classmembers’ claims for relief will produce a common answer”). It is only by establishing all of the elements of thefraud-on-the-market presumption that reliance can beproved on a classwide basis. Therefore, if a plaintiff wishes
to use Basic’s presumption to prove that reliance is acommon question, he must establish the entire presumption, including materiality, at the class certification stage.
Nor is it relevant, as respondent argues, that requiring
plaintiffs to establish all predicates of fraud on the market
at certification will make it more difficult to obtain certification. See Brief for Respondent 35–38. In Basic, four
Justices of a six-Justice Court created the fraud-on-themarket presumption from a combination of newly minted
economic theories, 485 U. S., at 250–251, n. 1 (White, J.,
concurring in part and dissenting in part), and “considerations of fairness, public policy, and probability,” id., at 245(majority opinion), to allow claims that otherwise would
have been barred due to the plaintiffs’ inability to show
reliance, id., at 242. Basic is a judicially invented doctrine
based on an economic theory adopted to ease the burden
on plaintiffs bringing claims under an implied cause ofaction. There is nothing untoward about requiring plaintiffs to take the steps that the Basic Court created in aneffort to save otherwise inadequate claims.

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THOMAS, J., dissenting

II
The majority’s approach is, thus, doctrinally incorrectunder Basic. Its shortcomings are further highlighted by
the role that materiality played in the pre-Basic development of the fraud-on-the-market theory as a condition
precedent to showing that there are common questions ofreliance in the class-action context. Materiality, at thetime of certification, has been a driving force behind
the theory from the outset. This fact further supports theneed to prove materiality at the time the fraud-on-themarket theory is invoked to show that questions of reliance can be answered on a classwide basis.
A
Before Basic, two signposts marked the way for courts
applying the fraud-on-the-market theory. Both demonstrate that the materiality of an alleged falsehood was nota mere afterthought but rather one of the primary reasonsfor allowing traditional proof of reliance to be brushedaside at certification. This fact weighs strongly in favor of
the conclusion that materiality must be resolved at certification when the fraud-on-the-market presumption is
invoked to show that reliance can be proved on a classwide
basis.
The first signpost was the Ninth Circuit’s 1975 opinion
in Blackie, termed by one pre-Basic court the “seminal
fraud on the market case.” Peil, 806 F. 2d, at 1163, n. 16.
See also Basic, supra, at 251, n. 1 (White, J., dissenting)(“The earliest Court of Appeals case adopting this theory
cited by the Court is Blackie v. Barrack, 524 F. 2d 891(CA9 1975), cert. denied, 429 U. S. 816 (1976)”).
Blackie arose from a $90 million loss reported by audio
equipment manufacturer Ampex Corp. in its 1972 annual
report. 524 F. 2d, at 894.10 Ampex’s independent auditors——————
10 Ampex’s sales for 1971 were just under $284 million.

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AND TRUST FUNDS
THOMAS, J., dissenting

not only refused to certify the 1972 annual report but also
withdrew certification of all 1971 financial statements“because of doubts that the loss reported for 1972 was infact suffered in that year.” Ibid. In resultant class actions, the defendants argued that reliance stood in theway of class certification under Rule 23(b)(3) because it
was not a common question.
The Ninth Circuit disagreed. Instead, it relieved plaintiffs from providing traditional proof of reliance, explaining that “causation is adequately established in theimpersonal stock exchange context by proof of purchase andof the materiality of misrepresentations, without direct proofof reliance.” Id., at 906 (emphasis added). The court left
no doubt that the materiality of the $90 million shortfall
in Ampex’s financial statements was central to its determination that reliance could be presumed. It asserted
that “[m]ateriality circumstantially establishes the reliance of some market traders and hence the inflation in thestock price—when the purchase is made[,] the causational
chain between defendant’s conduct and plaintiff ’s loss issufficiently established to make out a prima facie case.”
Ibid. Materiality was not merely an important factor thatallowed reliance to be presumed at certification; materiality was the factor. It demonstrated that the defendants
had committed a fraud on the market, that all putativeclass plaintiffs had relied on it in purchasing stock, and,
therefore, that questions of reliance would be susceptible
to common answers.11——————
A. & P. Registers Deficit for First Fiscal Quarter, N. Y. Times, July 1,
1972, p. 30 (discussing Ampex’s revenue and net loss in its 1972 Annual
Report).
11 Blackie’s use of materiality to satisfy reliance for purposes of Rule23(b)(3) predominance continued to form the foundation for the fraudon-the-market concept in subsequent pre-Basic appellate cases. See,e.g., Peil v. Speiser, 806 F. 2d 1154, 1161 (CA3 1986) (“[W]e hold thatplaintiffs who purchase in an open and developed market need not119Cite as: 568 U. S. ____ (2013)15

THOMAS, J., dissenting

The second fraud-on-the-market signpost prior to Basic
was a note in the Harvard Law Review, which described
the nascent theory. See Note, The Fraud-on-the-Market
Theory, 95 Harv. L. Rev. 1143 (1982) (hereinafter Harv.
L. Rev. Note). The Sixth Circuit opinion reviewed in Basictermed the Note “[t]he clearest statement of the theory ofpresumption of reliance.” Levinson v. Basic Inc., 786 F. 2d741, 750 (1986). Indeed, in the briefing for Basic itself,
the plaintiffs, the United States, and plaintiffs’ amicus citedthe article repeatedly as an authoritative statement on thesubject. See Brief for Respondent 43, n. 18, 46, n. 20 (cited
in Peil, supra, at 1160), Brief for Securities and Exchange
Commission as Amicus Curiae 22, n. 25, 24, n. 30, 26, n.
32, and Brief for Joseph Harris et al. as Amicus Curiae 4,
n. 2, in Basic Inc. v. Levinson, O. T. 1987, No. 86–279.
Like Blackie, the Note also hinged the fraud-on-themarket presumption of reliance on proof of materiality.
Harv. L. Rev. Note 1161 (“In developed markets, which
are apparently efficient, reliance should be presumed fromthe materiality of the deception” (emphasis added)). Ultimately, in language that will be familiar to anyone who
has read Basic, the Note formulated a “pivotal assumption” underlying the fraud-on-the-market theory as thebelief that:“market prices respond to information disseminated(or not disseminated) concerning the companies whose
securities are traded. In such a setting—often described as an ‘efficient market’—the reliance of sometraders upon a material deception influences market——————

prove direct reliance on defendants' misrepresentations, but can satisfy
their burden of proof on the element of causation by showing that thedefendants made material misrepresentations” (footnote omitted));Panzirer v. Wolf, 663 F. 2d 365, 368 (CA2 1981) (“Blackie held that themateriality of a fraud creates a presumption of reliance through its
presumed effect on the market. . . . Our holding is no more than anextension of Blackie”).

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AND TRUST FUNDS
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prices and thereby affects even traders who neverread or hear of the deception.” Harv. L. Rev. Note
1154 (footnote omitted).
Again, the materiality of the alleged misstatement wasa key component, without which the market could not be
presumed to move. As a result, without materiality it is
impossible to say that there has been a fraud on the market at all, and if that is not the case there is no reason tobelieve that the market price at which stock transactions
occurred was affected by an alleged misstatement or, byextension, that any market participants relied on it.
Materiality should thus be proved when the fraud-on-themarket presumption is invoked, or there is no commonality with respect to questions of reliance.
B
Nor did the importance of materiality diminish in the
Sixth Circuit opinion reviewed in Basic. Rather, the court
followed the path marked by the signposts discussed
above. It excused plaintiffs from offering traditional evidence of reliance, so long as “a defendant is shown to havemade a material public misrepresentation that, if relied
on directly, would fraudulently induce an individual to misjudge the value of the stock.” Levinson, 786 F. 2d, at 750(emphasis added). The court’s analysis made clear thatmateriality should be demonstrated at the time the presumption was invoked: “In order to invoke the presumption of reliance based upon the fraud on the market theory,a plaintiff must allege and prove . . . that the misrepresentations were material . . . .” Ibid. (citing Blackie,
524 F. 2d, at 906).
C
Finally, the briefing before this Court in Basic itself
built upon this framework and the foundational principlethat materiality is an integral part of the theory. Criti-

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THOMAS, J., dissenting

cally, the Basic defendants argued that the plaintiffs could
not establish fraud on the market at certification even if
the theory were valid because the alleged misstatement
was immaterial. They “contrast[ed] the likely market
impact of disclosure of the [$90 million Blackie loss] . . .
with the disclosure of the information which respondents
contend[ed] rendered Basic’s statements materially misleading.” See Brief for Petitioners in O. T. 1987, No. 86–
279, p. 42. The Basic defendants concluded that “thedifferences between a company’s $90 million loss and acompany’s sporadic contacts with a friendly suitor are substantial. . . . [T]he fraud on the market theory, if it hasvitality, should not be applied in a case such as this.” Id.,
at 43.
In response, the plaintiffs in Basic did not argue thatthe defendants misunderstood the role of materiality inthe fraud-on-the-market theory. They instead advanced anow-foreclosed interpretation of dicta from Eisen v. Carlisle & Jacquelin, 417 U. S. 156, 177 (1974):“Petitioners’ final argument—that respondents will be
unable to establish that Basic’s repeated false andmisleading statements impacted the price of Basicstock over a fourteen month period—represents an effort to litigate the merits of this case on the motion forclass certification. . . . As this Court held in Eisen v.
Carlisle & Jacquelin, 417 U. S. 156, 177 (1974): ‘We
find nothing in either the language or history of Rule
23 that gives a court any authority to conduct a preliminary inquiry into the merits of a suit in order todetermine whether it may be maintained as a classaction.’ ” Brief for Respondents in O. T. 1987, No. 86–
279, p. 54.
The Court rejected this reading of Eisen two Terms ago,
explaining that the very language the Basic plaintiffs
quoted was “sometimes mistakenly cited” as prohibiting

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AND TRUST FUNDS
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inquiry into “the propriety of certification under Rules
23(a) and (b).” Wal-Mart Stores, Inc., 564 U. S., at ___,
n. 6 (slip op., at 10, n. 6). That reading, the Court explained, “is the purest dictum and is contradicted by ourother cases.” Ibid. The Basic defendants’ reply is consistent with Wal-Mart:“Putative class representatives, such as respondents,
should not be permitted to invoke the fraud on themarket theory while, at the same time, arguing thatcourts may not make any preliminary inquiry into theclaimed impact on the market. See, e.g., Resp. Br.,
p. 54. By seeking the benefit of the presumption, respondents necessarily invite judicial scrutiny of thecircumstances in which it is invoked.” Reply Brief for
Petitioners in O. T. 1987, No. 86–279, p. 18.
Well said. The history of Basic is worth the volume ofargument offered by the majority. Cf. New York Trust Co.
v. Eisner, 256 U. S. 345, 349 (1921) (majority opinion of
Holmes, J.). Materiality was central to the development,
analysis, and adoption of the fraud-on-the-market theory
both before Basic and in Basic itself. Materiality, therefore, must be demonstrated to prove fraud on the market,
and until materiality of an alleged misstatement is shown
there is no reason to believe that all market participants
have relied equally on it. Otherwise individualized questions of reliance remain. This history confirms that materiality must be proved at the time that the theory is
invoked—i.e., at certification.
III
I, thus, would reverse the judgment of the Ninth Circuitand hold that a plaintiff invoking the fraud-on-the-market
presumption bears the burden to establish all the elements of fraud on the market at certification, including
the materiality of the alleged misstatement.

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資料３
(Slip Opinion)

OCTOBER TERM, 2013

1

Syllabus
NOTE: Where it is feasible, a syllabus (headnote) will be released, as is
being done in connection with this case, at the time the opinion is issued.
The syllabus constitutes no part of the opinion of the Court but has been
prepared by the Reporter of Decisions for the convenience of the reader.
See United States v. Detroit Timber & Lumber Co., 200 U. S. 321, 337.

SUPREME COURT OF THE UNITED STATES
Syllabus

HALLIBURTON CO. ET AL. v. ERICA P. JOHN FUND,
INC., FKA ARCHDIOCESE OF MILWAUKEE
SUPPORTING FUND, INC.
CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR
THE FIFTH CIRCUIT
No. 13–317.

Argued March 5, 2014—Decided June 23, 2014

Investors can recover damages in a private securities fraud action only
if they prove that they relied on the defendant’s misrepresentation in
deciding to buy or sell a company’s stock. In Basic Inc. v. Levinson,
485 U. S. 224, this Court held that investors could satisfy this reliance requirement by invoking a presumption that the price of stock
traded in an efficient market reflects all public, material information—including material misrepresentations. The Court also held,
however, that a defendant could rebut this presumption by showingthat the alleged misrepresentation did not actually affect the stock
price—that is, that it had no “price impact.”
Respondent Erica P. John Fund, Inc. (EPJ Fund), filed a putativeclass action against Halliburton and one of its executives (collectively
Halliburton), alleging that they made misrepresentations designed toinflate Halliburton’s stock price, in violation of section 10(b) of the
Securities Exchange Act of 1934 and Securities and Exchange Commission Rule 10b–5. The District Court initially denied EPJ Fund’sclass certification motion, and the Fifth Circuit affirmed. But thisCourt vacated that judgment, concluding that securities fraud plaintiffs need not prove loss causation—a causal connection between the
defendants’ alleged misrepresentations and the plaintiffs’ economic
losses—at the class certification stage in order to invoke Basic’s presumption of reliance. On remand, Halliburton argued that class certification was nonetheless inappropriate because the evidence it had
earlier introduced to disprove loss causation also showed that its alleged misrepresentations had not affected its stock price. By demonstrating the absence of any “price impact,” Halliburton contended, it

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Syllabus
had rebutted the Basic presumption. And without the benefit of that
presumption, investors would have to prove reliance on an individual
basis, meaning that individual issues would predominate over common ones and class certification would be inappropriate under Federal Rule of Civil Procedure 23(b)(3). The District Court rejected Halliburton’s argument and certified the class. The Fifth Circuit
affirmed, concluding that Halliburton could use its price impact evidence to rebut the Basic presumption only at trial, not at the classcertification stage.

Held:
1. Halliburton has not shown a “special justification,” Dickerson v.
United States, 530 U. S. 428, 443, for overruling Basic’s presumptionof reliance. Pp. 4–16.
(a) To recover damages under section 10(b) and Rule 10b–5, aplaintiff must prove, as relevant here, “ ‘reliance upon the misrepresentation or omission.’ ” Amgen Inc. v. Connecticut Retirement Plans
and Trust Funds, 568 U. S. ___, ___. The Court recognized in Basic,
however, that requiring direct proof of reliance from every individual
plaintiff “would place an unnecessarily unrealistic evidentiary burden on the . . . plaintiff who has traded on an impersonal market,”
485 U. S., at 245, and “effectively would” prevent plaintiffs “from proceeding with a class action” in Rule 10b–5 suits, id., at 242. To address these concerns, the Court held that plaintiffs could satisfy thereliance element of a Rule 10b–5 action by invoking a rebuttable presumption of reliance. The Court based that presumption on what is
known as the “fraud-on-the-market” theory, which holds that “themarket price of shares traded on well-developed markets reflects all
publicly available information, and, hence, any material misrepresentations.” Id., at 246. The Court also noted that the typical “investor who buys or sells stock at the price set by the market does so inreliance on the integrity of that price.” Id., at 247. As a result,whenever an investor buys or sells stock at the market price, his “reliance on any public material misrepresentations . . . may be presumed for purposes of a Rule 10b–5 action.” Id. at 247. Basic alsoemphasized that the presumption of reliance was rebuttable rather
than conclusive. Pp. 5–7.
(b) None of Halliburton’s arguments for overruling Basic so discredit the decision as to constitute a “special justification.” Pp. 7–12.
(1) Halliburton first argues that the Basic presumption is inconsistent with Congress’s intent in passing the 1934 Exchange Act—the same argument made by the dissenting Justices in Basic. The
Basic majority did not find that argument persuasive then, and Halliburton has given no new reason to endorse it now. Pp. 7–8.
(2) Halliburton also contends that Basic rested on two premis-

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Syllabus
es that have been undermined by developments in economic theory.
First, it argues that the Basic Court espoused “a robust view of market efficiency” that is no longer tenable in light of empirical evidence
ostensibly showing that material, public information often is not
quickly incorporated into stock prices. The Court in Basic acknowledged, however, the debate among economists about the efficiency of
capital markets and refused to endorse “any particular theory of how
quickly and completely publicly available information is reflected inmarket price.” 485 U. S., at 248, n. 28. The Court instead based thepresumption of reliance on the fairly modest premise that “market
professionals generally consider most publicly announced material
statements about companies, thereby affecting stock market prices.”
Id., at 247, n. 24. Moreover, in making the presumption rebuttable,
Basic recognized that market efficiency is a matter of degree and accordingly made it a matter of proof. Halliburton has not identified
the kind of fundamental shift in economic theory that could justify
overruling a precedent on the ground that it misunderstood, or has
since been overtaken by, economic realities.
Halliburton also contests the premise that investors “invest ‘in reliance on the integrity of [the market] price,’ ” id., at 247, identifying
a number of classes of investors for whom “price integrity” is supposedly “marginal or irrelevant.” But Basic never denied the existenceof such investors, who in any event rely at least on the facts thatmarket prices will incorporate public information within a reasonable
period and that market prices, however inaccurate, are not distorted
by fraud. Pp. 8–12.
(c) The principle of stare decisis has “ ‘special force’ ” “in respect
to statutory interpretation” because “ ‘Congress remains free to alter
what [the Court has] done.’ ” John R. Sand & Gravel Co. v. UnitedStates, 552 U. S. 130, 139. So too with Basic’s presumption of reliance. The presumption is not inconsistent with this Court’s more recent decisions construing the Rule 10b–5 cause of action. In Central
Bank of Denver, N. A. v. First Interstate Bank of Denver, N. A., 511
U. S. 164, and Stoneridge Investment Partners, LLC v. ScientificAtlanta, Inc., 552 U. S. 148, the Court declined to effectively eliminate the reliance element by extending liability to entirely new categories of defendants who themselves had not made any material,
public misrepresentation. The Basic presumption, by contrast, merely provides an alternative means of satisfying the reliance element.
Nor is the Basic presumption inconsistent with the Court’s recent decisions governing class action certification, which require plaintiffs toprove—not simply plead—that their proposed class satisfies each requirement of Federal Rule of Civil Procedure 23, including, if applicable, the predominance requirement of Rule 23(b)(3). See, e.g., Wal-

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Syllabus
Mart Stores, Inc. v. Dukes, 564 U. S. ___, ___. The Basic presumption
does not relieve plaintiffs of that burden but rather sets forth whatplaintiffs must prove to demonstrate predominance. Finally, Halliburton emphasizes the possible harmful consequences of the securities class actions facilitated by the Basic presumption, but such concerns are more appropriately addressed to Congress, which has infact responded, to some extent, to many of them. Pp. 12–16.
2. For the same reasons the Court declines to overrule Basic’s presumption of reliance, it also declines to modify the prerequisites forinvoking the presumption by requiring plaintiffs to prove “price impact” directly at the class certification stage. The Basic presumption
incorporates two constituent presumptions: First, if a plaintiff showsthat the defendant’s misrepresentation was public and material andthat the stock traded in a generally efficient market, he is entitled toa presumption that the misrepresentation affected the stock price.
Second, if the plaintiff also shows that he purchased the stock at themarket price during the relevant period, he is entitled to a further
presumption that he purchased the stock in reliance on the defendant’s misrepresentation. Requiring plaintiffs to prove price impact
directly would take away the first constituent presumption. Halliburton’s argument for doing so is the same as its argument for overruling the Basic presumption altogether, and it meets the same fate.
Pp. 16–18.
3. The Court agrees with Halliburton, however, that defendants
must be afforded an opportunity to rebut the presumption of reliance
before class certification with evidence of a lack of price impact. Defendants may already introduce such evidence at the merits stage torebut the Basic presumption, as well as at the class certification
stage to counter a plaintiff’s showing of market efficiency. Forbidding defendants to rely on the same evidence prior to class certification for the particular purpose of rebutting the presumption altogether makes no sense, and can readily lead to results that areinconsistent with Basic’s own logic. Basic allows plaintiffs to establish price impact indirectly, by showing that a stock traded in an efficient market and that a defendant’s misrepresentations were public
and material. But an indirect proxy should not preclude consideration of a defendant’s direct, more salient evidence showing that an alleged misrepresentation did not actually affect the stock’s price and,
consequently, that the Basic presumption does not apply. Amgendoes not require a different result. There, the Court held that materiality, though a prerequisite for invoking the Basic presumption,
should be left to the merits stage because it does not bear on the predominance requirement of Rule 23(b)(3). In contrast, the fact that amisrepresentation has price impact is “Basic’s fundamental premise.”127

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5

Syllabus
Erica P. John Fund, Inc. v. Halliburton Co., 563 U. S. ___, ___. It
thus has everything to do with the issue of predominance at the classcertification stage. That is why, if reliance is to be shown throughthe Basic presumption, the publicity and market efficiency prerequisites must be proved before class certification. Given that such indirect evidence of price impact will be before the court at the class certification stage in any event, there is no reason to artificially limit theinquiry at that stage by excluding direct evidence of price impact.
Pp. 18–23.
718 F. 3d 423, vacated and remanded.
ROBERTS, C. J., delivered the opinion of the Court, in which KENNEDY,GINSBURG, BREYER, SOTOMAYOR, and KAGAN, JJ., joined. GINSBURG, J.,
filed a concurring opinion, in which BREYER and SOTOMAYOR,
JJ., joined. THOMAS, J., filed an opinion concurring in the judgment, inwhich SCALIA and ALITO, JJ., joined.

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1

Opinion of the Court
NOTICE: This opinion is subject to formal revision before publication in the
preliminary print of the United States Reports. Readers are requested to
notify the Reporter of Decisions, Supreme Court of the United States, Washington, D. C. 20543, of any typographical or other formal errors, in orderthat corrections may be made before the preliminary print goes to press.

SUPREME COURT OF THE UNITED STATES_________________

No. 13–317_________________HALLIBURTON CO., ET AL., PETITIONERS v. ERICA P.
JOHN FUND, INC., FKA ARCHDIOCESE OFMILWAUKEE SUPPORTING FUND, INC.
ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF
APPEALS FOR THE FIFTH CIRCUIT[June 23, 2014]

CHIEF JUSTICE ROBERTS delivered the opinion of the
Court.
Investors can recover damages in a private securities
fraud action only if they prove that they relied on the
defendant’s misrepresentation in deciding to buy or sell acompany’s stock. In Basic Inc. v. Levinson, 485 U. S. 224(1988), we held that investors could satisfy this reliancerequirement by invoking a presumption that the price ofstock traded in an efficient market reflects all public,
material information—including material misstatements.
In such a case, we concluded, anyone who buys or sells thestock at the market price may be considered to have reliedon those misstatements.
We also held, however, that a defendant could rebut thispresumption in a number of ways, including by showingthat the alleged misrepresentation did not actually affectthe stock’s price—that is, that the misrepresentation had
no “price impact.” The questions presented are whether
we should overrule or modify Basic’s presumption of reliance and, if not, whether defendants should nonetheless

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Opinion of the Court

be afforded an opportunity in securities class action cases
to rebut the presumption at the class certification stage,by showing a lack of price impact.
I
Respondent Erica P. John Fund, Inc. (EPJ Fund), is thelead plaintiff in a putative class action against Halliburton
and one of its executives (collectively Halliburton) alleging
violations of section 10(b) of the Securities Exchange Actof 1934, 48 Stat. 891, 15 U. S. C. §78j(b), and Securities
and Exchange Commission Rule 10b–5, 17 CFR §240.10b–5(2013). According to EPJ Fund, between June 3, 1999,
and December 7, 2001, Halliburton made a series of misrepresentations regarding its potential liability in asbestos
litigation, its expected revenue from certain construction
contracts, and the anticipated benefits of its merger withanother company—all in an attempt to inflate the price of
its stock. Halliburton subsequently made a number ofcorrective disclosures, which, EPJ Fund contends, caused
the company’s stock price to drop and investors to losemoney.
EPJ Fund moved to certify a class comprising all investors who purchased Halliburton common stock during theclass period. The District Court found that the proposedclass satisfied all the threshold requirements of Federal
Rule of Civil Procedure 23(a): It was sufficiently numerous, there were common questions of law or fact, the representative parties’ claims were typical of the class claims,
and the representatives could fairly and adequately protect the interests of the class. App. to Pet. for Cert. 54a.
And except for one difficulty, the court would have also
concluded that the class satisfied the requirement of Rule23(b)(3) that “the questions of law or fact common to classmembers predominate over any questions affecting only
individual members.” See id., at 55a, 98a. The difficulty
was that Circuit precedent required securities fraud plain-

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3

Opinion of the Court

tiffs to prove “loss causation”—a causal connection between the defendants’ alleged misrepresentations and theplaintiffs’ economic losses—in order to invoke Basic’s
presumption of reliance and obtain class certification.
App. to Pet. for Cert. 55a, and n. 2. Because EPJ Fund
had not demonstrated such a connection for any of Halliburton’s alleged misrepresentations, the District Court
refused to certify the proposed class. Id., at 55a, 98a. The
United States Court of Appeals for the Fifth Circuit affirmed the denial of class certification on the same ground.
Archdiocese of Milwaukee Supporting Fund, Inc. v. Halliburton Co., 597 F. 3d 330 (2010).
We granted certiorari and vacated the judgment, finding
nothing in “Basic or its logic” to justify the Fifth Circuit’s
requirement that securities fraud plaintiffs prove losscausation at the class certification stage in order to invoke
Basic’s presumption of reliance. Erica P. John Fund, Inc.
v. Halliburton Co., 563 U. S. ___, ___ (2011) (Halliburton
I ) (slip op., at 6). “Loss causation,” we explained, “addresses a matter different from whether an investor relied
on a misrepresentation, presumptively or otherwise, whenbuying or selling a stock.” Ibid. We remanded the case forthe lower courts to consider “any further arguments
against class certification” that Halliburton had preserved.
Id., at ___ (slip op., at 9).
On remand, Halliburton argued that class certification
was inappropriate because the evidence it had earlier
introduced to disprove loss causation also showed thatnone of its alleged misrepresentations had actually affected its stock price. By demonstrating the absence of any“price impact,” Halliburton contended, it had rebutted
Basic’s presumption that the members of the proposedclass had relied on its alleged misrepresentations simply
by buying or selling its stock at the market price. And
without the benefit of the Basic presumption, investors
would have to prove reliance on an individual basis, mean-

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ing that individual issues would predominate over common ones. The District Court declined to consider Halliburton’s argument, holding that the Basic presumption
applied and certifying the class under Rule 23(b)(3). App.
to Pet. for Cert. 30a.
The Fifth Circuit affirmed. 718 F. 3d 423 (2013). The
court found that Halliburton had preserved its price impact argument, but to no avail. Id., at 435–436. Whileacknowledging that “Halliburton’s price impact evidence
could be used at the trial on the merits to refute the presumption of reliance,” id., at 433, the court held thatHalliburton could not use such evidence for that purposeat the class certification stage, id., at 435. “[P]rice impact
evidence,” the court explained, “does not bear on the question of common question predominance [under Rule23(b)(3)], and is thus appropriately considered only on the
merits after the class has been certified.” Ibid.
We once again granted certiorari, 571 U. S. ___ (2013),
this time to resolve a conflict among the Circuits overwhether securities fraud defendants may attempt to rebut
the Basic presumption at the class certification stage withevidence of a lack of price impact. We also accepted Halliburton’s invitation to reconsider the presumption of reliance for securities fraud claims that we adopted in Basic.
II
Halliburton urges us to overrule Basic’s presumption ofreliance and to instead require every securities fraud
plaintiff to prove that he actually relied on the defendant’s
misrepresentation in deciding to buy or sell a company’s
stock. Before overturning a long-settled precedent, however, we require “special justification,” not just an argument that the precedent was wrongly decided. Dickerson
v. United States, 530 U. S. 428, 443 (2000) (internal quotation marks omitted). Halliburton has failed to make thatshowing.

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A
Section 10(b) of the Securities Exchange Act of 1934 andthe Securities and Exchange Commission’s Rule 10b–5
prohibit making any material misstatement or omission inconnection with the purchase or sale of any security.
Although section 10(b) does not create an express privatecause of action, we have long recognized an implied private cause of action to enforce the provision and its implementing regulation. See Blue Chip Stamps v. Manor
Drug Stores, 421 U. S. 723, 730 (1975). To recover damages
for violations of section 10(b) and Rule 10b–5, a plaintiff
must prove “ ‘(1) a material misrepresentation or omission
by the defendant; (2) scienter; (3) a connection between themisrepresentation or omission and the purchase or sale ofa security; (4) reliance upon the misrepresentation oromission; (5) economic loss; and (6) loss causation.’ ”
Amgen Inc. v. Connecticut Retirement Plans and TrustFunds, 568 U. S. ___, ___ (2013) (slip op., at 3–4) (quoting
Matrixx Initiatives, Inc. v. Siracusano, 563 U. S. ___, ___(2011) (slip op., at 9)).
The reliance element “ ‘ensures that there is a proper
connection between a defendant’s misrepresentation and aplaintiff ’s injury.’ ” 568 U. S., at ___ (slip op., at 4) (quoting Halliburton I, 563 U. S., at ___ (slip op., at 4)). “Thetraditional (and most direct) way a plaintiff can demonstrate reliance is by showing that he was aware of a company’s statement and engaged in a relevant transaction—e.g., purchasing common stock—based on that specificmisrepresentation.” Id., at ___ (slip op., at 4).
In Basic, however, we recognized that requiring suchdirect proof of reliance “would place an unnecessarily
unrealistic evidentiary burden on the Rule 10b–5 plaintiff
who has traded on an impersonal market.” 485 U. S., at245. That is because, even assuming an investor could
prove that he was aware of the misrepresentation, hewould still have to “show a speculative state of facts, i.e.,

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how he would have acted . . . if the misrepresentation had
not been made.” Ibid.
We also noted that “[r]equiring proof of individualized
reliance” from every securities fraud plaintiff “effectively
would . . . prevent[ ] [plaintiffs] from proceeding with aclass action” in Rule 10b–5 suits. Id., at 242. If every
plaintiff had to prove direct reliance on the defendant’s
misrepresentation, “individual issues then would . . .
overwhelm[ ] the common ones,” making certification
under Rule 23(b)(3) inappropriate. Ibid.
To address these concerns, Basic held that securities
fraud plaintiffs can in certain circumstances satisfy thereliance element of a Rule 10b–5 action by invoking a
rebuttable presumption of reliance, rather than proving
direct reliance on a misrepresentation. The Court basedthat presumption on what is known as the “fraud-on-themarket” theory, which holds that “the market price ofshares traded on well-developed markets reflects all publicly available information, and, hence, any material misrepresentations.” Id., at 246. The Court also noted that,rather than scrutinize every piece of public information
about a company for himself, the typical “investor whobuys or sells stock at the price set by the market does so inreliance on the integrity of that price”—the belief that itreflects all public, material information. Id., at 247. As aresult, whenever the investor buys or sells stock at themarket price, his “reliance on any public material misrepresentations . . . may be presumed for purposes of a Rule10b–5 action.” Ibid.
Based on this theory, a plaintiff must make the following showings to demonstrate that the presumption ofreliance applies in a given case: (1) that the alleged misrepresentations were publicly known, (2) that they werematerial, (3) that the stock traded in an efficient market,
and (4) that the plaintiff traded the stock between thetime the misrepresentations were made and when the134

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truth was revealed. See id., at 248, n. 27; Halliburton I,
supra, at ___ (slip op., at 5–6).
At the same time, Basic emphasized that the presumption of reliance was rebuttable rather than conclusive.
Specifically, “[a]ny showing that severs the link between
the alleged misrepresentation and either the price received (or paid) by the plaintiff, or his decision to trade ata fair market price, will be sufficient to rebut the presumption of reliance.” 485 U. S., at 248. So for example, if
a defendant could show that the alleged misrepresentation
did not, for whatever reason, actually affect the market
price, or that a plaintiff would have bought or sold thestock even had he been aware that the stock’s price wastainted by fraud, then the presumption of reliance would
not apply. Id., at 248–249. In either of those cases, aplaintiff would have to prove that he directly relied on the
defendant’s misrepresentation in buying or selling thestock.
B
Halliburton contends that securities fraud plaintiffs
should always have to prove direct reliance and that the
Basic Court erred in allowing them to invoke a presumption of reliance instead. According to Halliburton, theBasic presumption contravenes congressional intent andhas been undermined by subsequent developments ineconomic theory. Neither argument, however, so discredits Basic as to constitute “special justification” for overruling the decision.
1
Halliburton first argues that the Basic presumption isinconsistent with Congress’s intent in passing the 1934
Exchange Act. Because “[t]he Section 10(b) action is a‘judicial construct that Congress did not enact,’ ” thisCourt, Halliburton insists, “must identify—and borrow

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from—the express provision that is ‘most analogous to theprivate 10b–5 right of action.’ ” Brief for Petitioners 12(quoting Stoneridge Investment Partners, LLC v. ScientificAtlanta, Inc., 552 U. S. 148, 164 (2008); Musick, Peeler& Garrett v. Employers Ins. of Wausau, 508 U. S. 286, 294(1993)). According to Halliburton, the closest analogue
to section 10(b) is section 18(a) of the Act, which creates an express private cause of action allowing investors to recover damages based on misrepresentations
made in certain regulatory filings. 15 U. S. C. §78r(a).
That provision requires an investor to prove that hebought or sold stock “in reliance upon” the defendant’s
misrepresentation. Ibid. In ignoring this direct reliancerequirement, the argument goes, the Basic Court relieved
Rule 10b–5 plaintiffs of a burden that Congress would
have imposed had it created the cause of action.
EPJ Fund contests both premises of Halliburton’s argument, arguing that Congress has affirmed Basic’s construction of section 10(b) and that, in any event, the closest analogue to section 10(b) is not section 18(a) but
section 9, 15 U. S. C. §78i—a provision that does not require actual reliance.
We need not settle this dispute. In Basic, the dissenting
Justices made the same argument based on section 18(a)that Halliburton presses here. See 485 U. S., at 257–258(White, J., concurring in part and dissenting in part). The
Basic majority did not find that argument persuasive
then, and Halliburton has given us no new reason toendorse it now.
2
Halliburton’s primary argument for overruling Basic isthat the decision rested on two premises that can no longer
withstand scrutiny. The first premise concerns what is
known as the “efficient capital markets hypothesis.” Basicstated that “the market price of shares traded on well-136

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developed markets reflects all publicly available information, and, hence, any material misrepresentations.”
Id., at 246. From that statement, Halliburton concludes
that the Basic Court espoused “a robust view of market
efficiency” that is no longer tenable, for “ ‘overwhelming
empirical evidence’ now ‘suggests that capital markets are
not fundamentally efficient.’ ” Brief for Petitioners 14–16(quoting Lev & de Villiers, Stock Price Crashes and 10b–5
Damages: A Legal, Economic, and Policy Analysis, 47
Stan. L. Rev 7, 20 (1994)). To support this contention,
Halliburton cites studies purporting to show that “public
information is often not incorporated immediately (muchless rationally) into market prices.” Brief for Petitioners
17; see id., at 16–20. See also Brief for Law Professors as
Amici Curiae 15–18.
Halliburton does not, of course, maintain that capital
markets are always inefficient. Rather, in its view, Basic’s
fundamental error was to ignore the fact that “ ‘efficiency
is not a binary, yes or no question.’ ” Brief for Petitioners
20 (quoting Langevoort, Basic at Twenty: Rethinking
Fraud on the Market, 2009 Wis. L. Rev. 151, 167)). The
markets for some securities are more efficient than themarkets for others, and even a single market can process
different kinds of information more or less efficiently,
depending on how widely the information is disseminatedand how easily it is understood. Brief for Petitioners at
20–21. Yet Basic, Halliburton asserts, glossed over thesenuances, assuming a false dichotomy that renders thepresumption of reliance both underinclusive and overinclusive: A misrepresentation can distort a stock’s market
price even in a generally inefficient market, and a misrepresentation can leave a stock’s market price unaffectedeven in a generally efficient one. Brief for Petitioners at
21.
Halliburton’s criticisms fail to take Basic on its own
terms. Halliburton focuses on the debate among econo-

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mists about the degree to which the market price of acompany’s stock reflects public information about thecompany—and thus the degree to which an investor canearn an abnormal, above-market return by trading onsuch information. See Brief for Financial Economists as
Amici Curiae 4–10 (describing the debate). That debate is
not new. Indeed, the Basic Court acknowledged it anddeclined to enter the fray, declaring that “[w]e need not
determine by adjudication what economists and social
scientists have debated through the use of sophisticatedstatistical analysis and the application of economic theory.” 485 U. S., at 246–247, n. 24. To recognize the presumption of reliance, the Court explained, was not “conclusively to adopt any particular theory of how quickly andcompletely publicly available information is reflected inmarket price.” Id., at 248, n. 28. The Court instead based
the presumption on the fairly modest premise that “market professionals generally consider most publicly announced material statements about companies, thereby
affecting stock market prices.” Id., at 247, n. 24. Basic’s
presumption of reliance thus does not rest on a “binary”
view of market efficiency. Indeed, in making the presumption rebuttable, Basic recognized that market efficiency is a matter of degree and accordingly made it amatter of proof.
The academic debates discussed by Halliburton have notrefuted the modest premise underlying the presumption ofreliance. Even the foremost critics of the efficient-capitalmarkets hypothesis acknowledge that public information
generally affects stock prices. See, e.g., Shiller, We’ll
Share the Honors, and Agree to Disagree, N. Y. Times,
Oct. 27, 2013, p. BU6 (“Of course, prices reflect available
information”). Halliburton also conceded as much in its
reply brief and at oral argument. See Reply Brief 13(“market prices generally respond to new, material information”); Tr. of Oral Arg. 7. Debates about the precise

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degree to which stock prices accurately reflect public information are thus largely beside the point. “That the . . .
price [of a stock] may be inaccurate does not detract fromthe fact that false statements affect it, and cause loss,”which is “all that Basic requires.” Schleicher v. Wendt,
618 F. 3d 679, 685 (CA7 2010) (Easterbrook, C. J.). Even
though the efficient capital markets hypothesis may have“garnered substantial criticism since Basic,” post, at 6
(THOMAS, J., concurring in judgment), Halliburton has not
identified the kind of fundamental shift in economic theory that could justify overruling a precedent on the groundthat it misunderstood, or has since been overtaken by,economic realities. Contrast State Oil Co. v. Khan, 522
U. S. 3 (1997), unanimously overruling Albrecht v. Herald
Co., 390 U. S. 145 (1968).
Halliburton also contests a second premise underlying
the Basic presumption: the notion that investors “invest‘in reliance on the integrity of [the market] price.’ ” Reply
Brief 14 (quoting 485 U. S., at 247; alteration in original).
Halliburton identifies a number of classes of investors forwhom “price integrity” is supposedly “marginal or irrelevant.” Reply Brief 14. The primary example is the value
investor, who believes that certain stocks are undervalued
or overvalued and attempts to “beat the market” by buying
the undervalued stocks and selling the overvalued ones.
Brief for Petitioners 15–16 (internal quotation marks
omitted). See also Brief for Vivendi S. A. as Amicus Curiae
3–10 (describing the investment strategies of day traders, volatility arbitragers, and value investors). If many
investors “are indifferent to prices,” Halliburton contends,
then courts should not presume that investors rely on the
integrity of those prices and any misrepresentations incorporated into them. Reply Brief 14.
But Basic never denied the existence of such investors.
As we recently explained, Basic concluded only that “it isreasonable to presume that most investors—knowing that

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they have little hope of outperforming the market in thelong run based solely on their analysis of publicly available information—will rely on the security’s market price as
an unbiased assessment of the security’s value in light ofall public information.” Amgen, 568 U. S., at ___ (slip op.,at 5) (emphasis added).
In any event, there is no reason to suppose that even
Halliburton’s main counterexample—the value investor—
is as indifferent to the integrity of market prices as Halliburton suggests. Such an investor implicitly relies on thefact that a stock’s market price will eventually reflectmaterial information—how else could the market correction on which his profit depends occur? To be sure, thevalue investor “does not believe that the market priceaccurately reflects public information at the time he transacts.” Post, at 11. But to indirectly rely on a misstatement in the sense relevant for the Basic presumption, he
need only trade stock based on the belief that the market
price will incorporate public information within a reasonable period. The value investor also presumably tries toestimate how undervalued or overvalued a particular
stock is, and such estimates can be skewed by a market
price tainted by fraud.
C
The principle of stare decisis has “ ‘special force’ ” “inrespect to statutory interpretation” because “ ‘Congress
remains free to alter what we have done.’ ” John R. Sand
& Gravel Co. v. United States, 552 U. S. 130, 139 (2008)(quoting Patterson v. McLean Credit Union, 491 U. S. 164,
172–173 (1989)). So too with Basic’s presumption of reliance. Although the presumption is a judicially createddoctrine designed to implement a judicially created causeof action, we have described the presumption as “a substantive doctrine of federal securities-fraud law.” Amgen,
supra, at ___ (slip op., at 5). That is because it provides a140

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way of satisfying the reliance element of the Rule 10b–5
cause of action. See, e.g., Dura Pharmaceuticals, Inc. v.
Broudo, 544 U. S. 336, 341–342 (2005). As with any otherelement of that cause of action, Congress may overturnor modify any aspect of our interpretations of the reliance requirement, including the Basic presumption itself. Given that possibility, we see no reason to exempt
the Basic presumption from ordinary principles of stare
decisis.
To buttress its case for overruling Basic, Halliburton
contends that, in addition to being wrongly decided, thedecision is inconsistent with our more recent decisions
construing the Rule 10b–5 cause of action. As Halliburton
notes, we have held that “we must give ‘narrow dimensions . . . to a right of action Congress did not authorize
when it first enacted the statute and did not expand when
it revisited the law.’ ” Janus Capital Group, Inc. v. First
Derivative Traders, 564 U. S. ___, ___ (2011) (slip op., at 6)(quoting Stoneridge, 552 U. S., at 167); see, e.g., Central
Bank of Denver, N. A. v. First Interstate Bank of Denver,
N. A., 511 U. S. 164 (1994) (refusing to recognize aidingand-abetting liability under the Rule 10b–5 cause of action); Stoneridge, supra (refusing to extend Rule 10b–5
liability to certain secondary actors who did not themselves make material misstatements). Yet the Basicpresumption, Halliburton asserts, does just the opposite,
expanding the Rule 10b–5 cause of action. Brief for Petitioners 27–29.
Not so. In Central Bank and Stoneridge, we declined toextend Rule 10b–5 liability to entirely new categories ofdefendants who themselves had not made any material,
public misrepresentation. Such an extension, we explained, would have eviscerated the requirement that aplaintiff prove that he relied on a misrepresentation madeby the defendant. See Central Bank, supra, at 180; Stoneridge, supra, at 157, 159. The Basic presumption does

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not eliminate that requirement but rather provides analternative means of satisfying it. While the presumption
makes it easier for plaintiffs to prove reliance, it does notalter the elements of the Rule 10b–5 cause of action andthus maintains the action’s original legal scope.
Halliburton also argues that the Basic presumption
cannot be reconciled with our recent decisions governingclass action certification under Federal Rule of Civil Procedure 23. Those decisions have made clear that plaintiffs
wishing to proceed through a class action must actually
prove—not simply plead—that their proposed class satisfies each requirement of Rule 23, including (if applicable)
the predominance requirement of Rule 23(b)(3). See WalMart Stores, Inc. v. Dukes, 564 U. S. ___, ___ (2011) (slipop., at 10); Comcast Corp. v. Behrend, 569 U. S. ___, ___(2013) (slip op., at 5–6). According to Halliburton, Basicrelieves Rule 10b–5 plaintiffs of that burden, allowing
courts to presume that common issues of reliance predominate over individual ones.
That is not the effect of the Basic presumption. In
securities class action cases, the crucial requirement forclass certification will usually be the predominance requirement of Rule 23(b)(3). The Basic presumption does
not relieve plaintiffs of the burden of proving—before classcertification—that this requirement is met. Basic instead
establishes that a plaintiff satisfies that burden by proving the prerequisites for invoking the presumption—
namely, publicity, materiality, market efficiency, andmarket timing. The burden of proving those prerequisites
still rests with plaintiffs and (with the exception of materiality) must be satisfied before class certification. Basic
does not, in other words, allow plaintiffs simply to pleadthat common questions of reliance predominate over individual ones, but rather sets forth what they must prove todemonstrate such predominance.
Basic does afford defendants an opportunity to rebut the142

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presumption of reliance with respect to an individual
plaintiff by showing that he did not rely on the integrity ofthe market price in trading stock. While this has theeffect of “leav[ing] individualized questions of reliance inthe case,” post, at 12, there is no reason to think that thesequestions will overwhelm common ones and render classcertification inappropriate under Rule 23(b)(3). That thedefendant might attempt to pick off the occasional classmember here or there through individualized rebuttal
does not cause individual questions to predominate.
Finally, Halliburton and its amici contend that, byfacilitating securities class actions, the Basic presumption
produces a number of serious and harmful consequences.
Such class actions, they say, allow plaintiffs to extort large
settlements from defendants for meritless claims; punish
innocent shareholders, who end up having to pay settlements and judgments; impose excessive costs on businesses;
and consume a disproportionately large share of judicial
resources. Brief for Petitioners 39–45.
These concerns are more appropriately addressed toCongress, which has in fact responded, to some extent, tomany of the issues raised by Halliburton and its amici.
Congress has, for example, enacted the Private Securities
Litigation Reform Act of 1995 (PSLRA), 109 Stat. 737,
which sought to combat perceived abuses in securities
litigation with heightened pleading requirements, limits
on damages and attorney’s fees, a “safe harbor” for certain
kinds of statements, restrictions on the selection of leadplaintiffs in securities class actions, sanctions for frivolous
litigation, and stays of discovery pending motions to dismiss. See Amgen, 568 U. S., at ___ (slip op., at 19–20).
And to prevent plaintiffs from circumventing these restrictions by bringing securities class actions under state
law in state court, Congress also enacted the Securities
Litigation Uniform Standards Act of 1998, 112 Stat. 3227,
which precludes many state law class actions alleging

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securities fraud. See Amgen, supra, at ___ (slip op., at 20).
Such legislation demonstrates Congress’s willingness toconsider policy concerns of the sort that Halliburton says
should lead us to overrule Basic.
III
Halliburton proposes two alternatives to overruling
Basic that would alleviate what it regards as the decision’s
most serious flaws. The first alternative would require
plaintiffs to prove that a defendant’s misrepresentation
actually affected the stock price—so-called “price impact”—in order to invoke the Basic presumption. It should
not be enough, Halliburton contends, for plaintiffs todemonstrate the general efficiency of the market in which
the stock traded. Halliburton’s second proposed alternative would allow defendants to rebut the presumption ofreliance with evidence of a lack of price impact, not only at
the merits stage—which all agree defendants may alreadydo—but also before class certification.
A
As noted, to invoke the Basic presumption, a plaintiff
must prove that: (1) the alleged misrepresentations were
publicly known, (2) they were material, (3) the stock tradedin an efficient market, and (4) the plaintiff traded thestock between when the misrepresentations were madeand when the truth was revealed. See Basic, 485 U. S., at248, n. 27; Amgen, supra, at ___ (slip op., at 15). Each ofthese requirements follows from the fraud-on-the-market
theory underlying the presumption. If the misrepresentation was not publicly known, then it could not have distorted the stock’s market price. So too if the misrepresentation was immaterial—that is, if it would not have “ ‘been
viewed by the reasonable investor as having significantly
altered the “total mix” of information made available,’ ”
Basic, supra, at 231–232 (quoting TSC Industries, Inc. v.

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Northway, Inc., 426 U. S. 438, 449 (1976))—or if the market in which the stock traded was inefficient. And if theplaintiff did not buy or sell the stock after the misrepresentation was made but before the truth was revealed,then he could not be said to have acted in reliance on a
fraud-tainted price.
The first three prerequisites are directed at price impact—“whether the alleged misrepresentations affected
the market price in the first place.” Halliburton I, 563
U. S., at ___ (slip op., at 8). In the absence of price impact,
Basic’s fraud-on-the-market theory and presumption ofreliance collapse. The “fundamental premise” underlying
the presumption is “that an investor presumptively relies
on a misrepresentation so long as it was reflected in themarket price at the time of his transaction.” 563 U. S., at___ (slip op., at 7). If it was not, then there is “no grounding for any contention that [the] investor[ ] indirectlyrelied on th[at] misrepresentation[ ] through [his] relianceon the integrity of the market price.” Amgen, supra, at ___(slip op., at 17).
Halliburton argues that since the Basic presumption
hinges on price impact, plaintiffs should be required toprove it directly in order to invoke the presumption.
Proving the presumption’s prerequisites, which are at best
an imperfect proxy for price impact, should not suffice.
Far from a modest refinement of the Basic presumption,
this proposal would radically alter the required showing
for the reliance element of the Rule 10b–5 cause of action.
What is called the Basic presumption actually incorporates two constituent presumptions: First, if a plaintiff
shows that the defendant’s misrepresentation was public
and material and that the stock traded in a generally
efficient market, he is entitled to a presumption that themisrepresentation affected the stock price. Second, if theplaintiff also shows that he purchased the stock at themarket price during the relevant period, he is entitled to a

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further presumption that he purchased the stock in reliance on the defendant’s misrepresentation.
By requiring plaintiffs to prove price impact directly,
Halliburton’s proposal would take away the first constituent presumption. Halliburton’s argument for doing so is
the same as its primary argument for overruling the Basicpresumption altogether: Because market efficiency is not a
yes-or-no proposition, a public, material misrepresentation
might not affect a stock’s price even in a generally efficient
market. But as explained, Basic never suggested otherwise; that is why it affords defendants an opportunity torebut the presumption by showing, among other things,
that the particular misrepresentation at issue did notaffect the stock’s market price. For the same reasons wedeclined to completely jettison the Basic presumption, we
decline to effectively jettison half of it by revising theprerequisites for invoking it.
B
Even if plaintiffs need not directly prove price impact toinvoke the Basic presumption, Halliburton contends that
defendants should at least be allowed to defeat the presumption at the class certification stage through evidence
that the misrepresentation did not in fact affect the stock
price. We agree.
1
There is no dispute that defendants may introduce such
evidence at the merits stage to rebut the Basic presumption. Basic itself “made clear that the presumption wasjust that, and could be rebutted by appropriate evidence,”
including evidence that the asserted misrepresentation (orits correction) did not affect the market price of the defendant’s stock. Halliburton I, supra, at ___ (slip op., at5); see Basic, supra, at 248.
Nor is there any dispute that defendants may introduce

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price impact evidence at the class certification stage, solong as it is for the purpose of countering a plaintiff’s
showing of market efficiency, rather than directly rebutting the presumption. As EPJ Fund acknowledges, “[o]fcourse . . . defendants can introduce evidence at classcertification of lack of price impact as some evidence thatthe market is not efficient.” Brief for Respondent 53. See
also Brief for United States as Amicus Curiae 26.
After all, plaintiffs themselves can and do introduce
evidence of the existence of price impact in connection with“event studies”—regression analyses that seek to showthat the market price of the defendant’s stock tends to
respond to pertinent publicly reported events. See Brief
for Law Professors as Amici Curiae 25–28. In this case,for example, EPJ Fund submitted an event study of various episodes that might have been expected to affect theprice of Halliburton’s stock, in order to demonstrate thatthe market for that stock takes account of material, public
information about the company. See App. 217–230 (describing the results of the study). The episodes examined
by EPJ Fund’s event study included one of the alleged
misrepresentations that form the basis of the Fund’s suit.
See id., at 230, 343–344. See also In re Xcelera.com Securities Litigation, 430 F. 3d 503, 513 (CA1 2005) (event
study included effect of misrepresentation challenged in
the case).
Defendants—like plaintiffs—may accordingly submit
price impact evidence prior to class certification. Whatdefendants may not do, EPJ Fund insists and the Court ofAppeals held, is rely on that same evidence prior to classcertification for the particular purpose of rebutting thepresumption altogether.
This restriction makes no sense, and can readily lead tobizarre results. Suppose a defendant at the certification
stage submits an event study looking at the impact on theprice of its stock from six discrete events, in an effort to

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refute the plaintiffs’ claim of general market efficiency.
All agree the defendant may do this. Suppose one of thesix events is the specific misrepresentation asserted by theplaintiffs. All agree that this too is perfectly acceptable.
Now suppose the district court determines that, despite
the defendant’s study, the plaintiff has carried its burden
to prove market efficiency, but that the evidence shows no
price impact with respect to the specific misrepresentation
challenged in the suit. The evidence at the certification
stage thus shows an efficient market, on which the alleged
misrepresentation had no price impact. And yet under
EPJ Fund’s view, the plaintiffs’ action should be certified
and proceed as a class action (with all that entails), eventhough the fraud-on-the-market theory does not apply andcommon reliance thus cannot be presumed.
Such a result is inconsistent with Basic’s own logic.
Under Basic’s fraud-on-the-market theory, market efficiency and the other prerequisites for invoking the presumption constitute an indirect way of showing priceimpact. As explained, it is appropriate to allow plaintiffs
to rely on this indirect proxy for price impact, rather thanrequiring them to prove price impact directly, given
Basic’s rationales for recognizing a presumption of reliance in the first place. See supra, at 6–7, 16–17.
But an indirect proxy should not preclude direct evidence when such evidence is available. As we explained in
Basic, “[a]ny showing that severs the link between the
alleged misrepresentation and . . . the price received (orpaid) by the plaintiff . . . will be sufficient to rebut thepresumption of reliance” because “the basis for findingthat the fraud had been transmitted through market pricewould be gone.” 485 U. S., at 248. And without the presumption of reliance, a Rule 10b–5 suit cannot proceed asa class action: Each plaintiff would have to prove relianceindividually, so common issues would not “predominate”
over individual ones, as required by Rule 23(b)(3). Id., at148

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242. Price impact is thus an essential precondition for any
Rule 10b–5 class action. While Basic allows plaintiffs toestablish that precondition indirectly, it does not require
courts to ignore a defendant’s direct, more salient evidence
showing that the alleged misrepresentation did not actuallyaffect the stock’s market price and, consequently, thatthe Basic presumption does not apply.
2
The Court of Appeals relied on our decision in Amgen in
holding that Halliburton could not introduce evidence oflack of price impact at the class certification stage. The
question in Amgen was whether plaintiffs could be required to prove (or defendants be permitted to disprove)materiality before class certification. Even though materiality is a prerequisite for invoking the Basic presumption, we held that it should be left to the merits stage,
because it does not bear on the predominance requirementof Rule 23(b)(3). We reasoned that materiality is an objective issue susceptible to common, classwide proof. 568
U. S., at ___ (slip op., at 11). We also noted that a failure
to prove materiality would necessarily defeat every plaintiff ’s claim on the merits; it would not simply preclude
invocation of the presumption and thereby cause individualquestions of reliance to predominate over common ones.
Ibid. See also id., at ___ (slip op., at 17–18). In this latter
respect, we explained, materiality differs from the publicity
and market efficiency prerequisites, neither of which isnecessary to prove a Rule 10b–5 claim on the merits. Id.,
at ___–___ (slip op., at 16–18).
EPJ Fund argues that much of the foregoing could besaid of price impact as well. Fair enough. But price impact differs from materiality in a crucial respect. Given
that the other Basic prerequisites must still be proved at
the class certification stage, the common issue of materiality can be left to the merits stage without risking the

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certification of classes in which individual issues will end
up overwhelming common ones. And because materiality
is a discrete issue that can be resolved in isolation fromthe other prerequisites, it can be wholly confined to themerits stage.
Price impact is different. The fact that a misrepresentation “was reflected in the market price at the time of [the]transaction”—that it had price impact—is “Basic’s fundamental premise.” Halliburton I, 563 U. S., at ___ (slip op.,at 7). It thus has everything to do with the issue of predominance at the class certification stage. That is why, if
reliance is to be shown through the Basic presumption,
the publicity and market efficiency prerequisites must be
proved before class certification. Without proof of thoseprerequisites, the fraud-on-the-market theory underlying
the presumption completely collapses, rendering classcertification inappropriate.
But as explained, publicity and market efficiency arenothing more than prerequisites for an indirect showing ofprice impact. There is no dispute that at least such indirect proof of price impact “is needed to ensure that thequestions of law or fact common to the class will ‘predominate.’ ” Amgen, 568 U. S., at ___ (slip op., at 10) (emphasis
deleted); see id., at ___ (slip op., at 16–17). That is so eventhough such proof is also highly relevant at the merits
stage.
Our choice in this case, then, is not between allowing
price impact evidence at the class certification stage orrelegating it to the merits. Evidence of price impact will
be before the court at the certification stage in any event.
The choice, rather, is between limiting the price impact
inquiry before class certification to indirect evidence, or
allowing consideration of direct evidence as well. As
explained, we see no reason to artificially limit the inquiry
at the certification stage to indirect evidence of priceimpact. Defendants may seek to defeat the Basic pre-150

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sumption at that stage through direct as well as indirect
price impact evidence.
***
More than 25 years ago, we held that plaintiffs could
satisfy the reliance element of the Rule 10b–5 cause ofaction by invoking a presumption that a public, material
misrepresentation will distort the price of stock traded inan efficient market, and that anyone who purchases thestock at the market price may be considered to have done
so in reliance on the misrepresentation. We adhere to thatdecision and decline to modify the prerequisites for invoking the presumption of reliance. But to maintain theconsistency of the presumption with the class certification
requirements of Federal Rule of Civil Procedure 23, defendants must be afforded an opportunity before classcertification to defeat the presumption through evidence
that an alleged misrepresentation did not actually affectthe market price of the stock.
Because the courts below denied Halliburton that opportunity, we vacate the judgment of the Court of Appeals for
the Fifth Circuit and remand the case for further proceedings consistent with this opinion.
It is so ordered.

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GINSBURG, J., concurring

SUPREME COURT OF THE UNITED STATES_________________

No. 13–317_________________HALLIBURTON CO., ET AL., PETITIONERS v. ERICA P.
JOHN FUND, INC., FKA ARCHDIOCESE OFMILWAUKEE SUPPORTING FUND, INC.
ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF
APPEALS FOR THE FIFTH CIRCUIT[June 23, 2014]JUSTICE GINSBURG, with whom JUSTICE BREYER andJUSTICE SOTOMAYOR join, concurring.
Advancing price impact consideration from the merits
stage to the certification stage may broaden the scope of
discovery available at certification. See Tr. of Oral Arg.
36–37. But the Court recognizes that it is incumbent upon
the defendant to show the absence of price impact. Seeante, at 17–18. The Court’s judgment, therefore, should
impose no heavy toll on securities-fraud plaintiffs withtenable claims. On that understanding, I join the Court’s
opinion.

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THOMAS, J., concurring in judgment

SUPREME COURT OF THE UNITED STATES_________________

No. 13–317_________________HALLIBURTON CO., ET AL., PETITIONERS v. ERICA P.
JOHN FUND, INC., FKA ARCHDIOCESE OFMILWAUKEE SUPPORTING FUND, INC.
ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF
APPEALS FOR THE FIFTH CIRCUIT[June 23, 2014]JUSTICE THOMAS, with whom JUSTICE SCALIA andJUSTICE ALITO join, concurring in the judgment.
The implied Rule 10b–5 private cause of action is “arelic of the heady days in which this Court assumed
common-law powers to create causes of action,” Correctional Services Corp. v. Malesko, 534 U. S. 61, 75 (2001)(SCALIA, J., concurring); see, e.g., J. I. Case Co. v. Borak,
377 U. S. 426, 433 (1964). We have since ended thatpractice because the authority to fashion private remedies
to enforce federal law belongs to Congress alone. Stoneridge Investment Partners, LLC v. Scientific-Atlanta, Inc.,
552 U. S. 148, 164 (2008). Absent statutory authorization
for a cause of action, “courts may not create one, no matter
how desirable that might be as a policy matter.” Alexander v. Sandoval, 532 U. S. 275, 286–287 (2001).
Basic Inc. v. Levinson, 485 U. S. 224 (1988), demonstrates the wisdom of this rule. Basic presented the question how investors must prove the reliance element of theimplied Rule 10b–5 cause of action—the requirement thatthe plaintiff buy or sell stock in reliance on the defendant’s
misstatement—when they transact on modern, impersonal
securities exchanges. Were the Rule 10b–5 action statutory, the Court could have resolved this question by interpreting the statutory language. Without a statute to

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HALLIBURTON CO. v. ERICA P. JOHN FUND, INC.
THOMAS, J., concurring in judgmentinterpret for guidance, however, the Court began insteadwith a particular policy “problem”: for investors in impersonal markets, the traditional reliance requirement was
hard to prove and impossible to prove as common among
plaintiffs bringing 10b–5 class-action suits. Id., at 242,
245. With the task thus framed as “resol[ving]” that“ ‘problem’ ” rather than interpreting statutory text, id., at242, the Court turned to nascent economic theory andnaked intuitions about investment behavior in its efforts
to fashion a new, easier way to meet the reliance requirement. The result was an evidentiary presumption, basedon a “fraud on the market” theory, that paved the way forclass actions under Rule 10b–5.
Today we are asked to determine whether Basic wascorrectly decided. The Court suggests that it was, andthat stare decisis demands that we preserve it. I disagree.
Logic, economic realities, and our subsequent jurisprudence have undermined the foundations of the Basic presumption, and stare decisis cannot prop up the façade thatremains. Basic should be overruled.
I
Understanding where Basic went wrong requires an
explanation of the “reliance” requirement as traditionally
understood.
“Reliance by the plaintiff upon the defendant’s deceptive
acts is an essential element” of the implied 10b–5 privatecause of action.1 Stoneridge, supra, at 159. To prove——————
1 As the private Rule 10b–5 action has evolved, the Court has drawn

on the common-law action of deceit to identify six elements a private
plaintiff must prove: “ ‘(1) a material misrepresentation or omission by
the defendant; (2) scienter; (3) a connection between the misrepresentation or omission and the purchase or sale of a security; (4) reliance upon
the misrepresentation or omission; (5) economic loss; and (6) losscausation.’ ” Amgen Inc. v. Connecticut Retirement Plans and TrustFunds, 568 U. S. ___, ___–___ (2013) (slip op., at 3–4).

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reliance, the plaintiff must show “ ‘transaction causation,’ ”
i.e., that the specific misstatement induced “the investor’s
decision to engage in the transaction.” Erica P. John
Fund, Inc. v. Halliburton Co., 563 U. S. ___, ___–___(2011) (slip op., at 6–7). Such proof “ensures that there isa proper ‘connection between a defendant’s misrepresentation and a plaintiff ’s injury’ ”—namely, that the plaintiff
has not just lost money as a result of the misstatement,
but that he was actually defrauded by it. Id., at ___ (slipop., at 4); see also Dirks v. SEC, 463 U. S. 646, 666–667, n.
27 (1983) (“[T]o constitute a violation of Rule 10b–5, there
must be fraud. . . . [T]here always are winners and losers;
but those who have ‘lost’ have not necessarily been defrauded”). Without that connection, Rule 10b–5 is reduced
to a “ ‘scheme of investor’s insurance,’ ” because a plaintiff
could recover whenever the defendant’s misstatement
distorted the stock price—regardless of whether the misstatement had actually tricked the plaintiff into buying (orselling) the stock in the first place. Dura Pharmaceuticals, Inc. v. Broudo, 544 U. S. 336, 345 (2005) (quoting
Basic, supra, at 252 (White, J., concurring in part anddissenting in part)).
The “traditional” reliance element requires a plaintiff to“sho[w] that he was aware of a company’s statement andengaged in a relevant transaction . . . based on that specific misrepresentation.” Erica P. John Fund, supra, at ___(slip op., at 4). But investors who purchase stock fromthird parties on impersonal exchanges (e.g., the New York
Stock Exchange) often will not be aware of any particularstatement made by the issuer of the security, and therefore cannot establish that they transacted based on a
specific misrepresentation. Nor is the traditional reliancerequirement amenable to class treatment; the inherently
individualized nature of the reliance inquiry renders it
impossible for a 10b–5 plaintiff to prove that common
questions predominate over individual ones, making class

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certification improper. See Basic, supra, at 242; Fed. Rule
Civ. Proc. 23(b)(3).
Citing these difficulties of proof and class certification,
485 U. S., at 242, 245, the Basic Court dispensed with thetraditional reliance requirement in favor of a new one
based on the fraud-on-the-market theory.2 The new version of reliance had two related parts.
First, Basic suggested that plaintiffs could meet thereliance requirement “ ‘indirectly,’ ” id., at 245. The Court
reasoned that “ ‘ideally, [the market] transmits information to the investor in the processed form of a market
price.’ ” Id., at 244. An investor could thus be said to have“relied” on a specific misstatement if (1) the market had
incorporated that statement into the market price of the
security, and (2) the investor then bought or sold that
security “in reliance on the integrity of the [market] price,”
id., at 247, i.e., based on his belief that the market price“ ‘reflect[ed]’ ” the stock’s underlying “ ‘value,’ ” id., at 244.
Second, Basic created a presumption that this “indirect”
form of “reliance” had been proved. Based primarily on
certain assumptions about economic theory and investor
behavior, Basic afforded plaintiffs who traded in efficient
markets an evidentiary presumption that both steps of thenovel reliance requirement had been satisfied—that (1)the market had incorporated the specific misstatement
into the market price of the security, and (2) the plaintiff——————
2 In the years preceding Basic, lower courts and commentators experimented with various ways to facilitate 10b–5 class actions by relaxing
or eliminating the reliance element of the implied 10b–5 action. See,e.g., Blackie v. Barrack, 524 F. 2d 891 (CA9 1975); Note, The Fraud-onthe-Market Theory, 95 Harv. L. Rev. 1143 (1982); Note, The Reliance
Requirement in Private Actions under SEC Rule 10b–5, 88 Harv. L.
Rev. 584, 592–606 (1975). The “fraud-on-the-market theory” is anumbrella term for those varied efforts. Black, Fraud on the Market: A
Criticism of Dispensing with Reliance Requirements in Certain Open
Market Transactions, 62 N. C. L. Rev. 435, 439–457 (1984).

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did transact in reliance on the integrity of that price.3 Id.,
at 247. A defendant was ostensibly entitled to rebut thepresumption by putting forth evidence that either of those
steps was absent. Id., at 248.
II
Basic’s reimagined reliance requirement was a mistake,and the passage of time has compounded its failings.
First, the Court based both parts of the presumption ofreliance on a questionable understanding of disputed
economic theory and flawed intuitions about investor
behavior. Second, Basic’s rebuttable presumption is at
odds with our subsequent Rule 23 cases, which require
plaintiffs seeking class certification to “ ‘affirmatively
demonstrate’ ” certification requirements like the predominance of common questions. Comcast Corp. v. Behrend,
569 U. S. ___, ___ (2013) (slip op., at 5) (quoting Wal-MartStores, Inc. v. Dukes, 564 U. S. ___, ___ (2011) (slip op., at10)). Finally, Basic’s presumption that investors rely on
the integrity of the market price is virtually irrebuttablein practice, which means that the “essential” relianceelement effectively exists in name only.
A
Basic based the presumption of reliance on two factualassumptions. The first assumption was that, in a “welldeveloped market,” public statements are generally “reflected” in the market price of securities. 485 U. S., at247. The second was that investors in such markets
transact “in reliance on the integrity of that price.” Ibid.
——————
3 An investor could invoke this presumption by demonstrating certain
predicates: (1) a public statement; (2) an efficient market; (3) that theshares were traded after the statement was made but before the truth
was revealed; and (4) that the statement was material. Basic, 485
U. S., at 248, n. 27.

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In other words, the Court created a presumption that aplaintiff had met the two-part, fraud-on-the-market version of the reliance requirement because, in the Court’sview, “common sense and probability” suggested that eachof those parts would be met. Id., at 246.
In reality, both of the Court’s key assumptions arehighly contestable and do not provide the necessary support for Basic’s presumption of reliance. The first assumption—that public statements are “reflected” in the market
price—was grounded in an economic theory that has
garnered substantial criticism since Basic. The second assumption—that investors categorically rely on the integrityof the market price—is simply wrong.
1
The Court’s first assumption was that “most publicly
available information”—including public misstatements—“is reflected in [the] market price” of a security. Id., at247. The Court grounded that assumption in “empiricalstudies” testing a then-nascent economic theory known as
the efficient capital markets hypothesis. Id., at 246–247.
Specifically, the Court relied upon the “semi-strong” version of that theory, which posits that the average investor
cannot earn above-market returns (i.e., “beat the market”)
in an efficient market by trading on the basis of publicly
available information. See, e.g., Stout, The Mechanisms ofMarket Inefficiency: An Introduction to the New Finance,
28 J. Corp. L. 635, 640, and n. 24 (2003) (citing Fama,
Efficient Capital Markets: A Review of Theory and Empirical Work, 25 J. Finance 383, 388 (1970)).4 The upshot of——————
4 The “weak form” of the hypothesis provides that an investor cannot
earn an above-market return by trading on historical price data. See
Dunbar & Heller, Fraud on the Market Meets Behavioral Finance, 31
Del. J. Corporate L. 455, 463–464 (2006) (hereinafter Dunbar & Heller).
The “strong form” provides that investors cannot achieve above-market
returns even by trading on nonpublic information. See ibid. The weak158

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the hypothesis is that “the market price of shares tradedon well-developed markets [will] reflec[t] all publicly
available information, and, hence, any material misrepresentations.” Basic, supra, at 246. At the time of Basic,
this version of the efficient capital markets hypothesis was“widely accepted.” See Dunbar & Heller 463–464.
This view of market efficiency has since lost its luster.
See, e.g., Langevoort, Basic at Twenty: Rethinking Fraudon the Market, 2009 Wis. L. Rev. 151, 175 (“Doubts about
the strength and pervasiveness of market efficiency aremuch greater today than they were in the mid-1980s”). As
it turns out, even “well-developed” markets (like the New
York Stock Exchange) do not uniformly incorporate information into market prices with high speed. “[F]riction inaccessing public information” and the presence of “processing costs” means that “not all public information will
be impounded in a security’s price with the same alacrity,or perhaps with any quickness at all.” Cox, Understanding Causation in Private Securities Lawsuits: Building on
Amgen, 66 Vand. L. Rev. 1719, 1732 (2013) (hereinafter
Cox). For example, information that is easily digestible(merger announcements or stock splits) or especiallyprominent (Wall Street Journal articles) may be incorporated quickly, while information that is broadly applicableor technical (Securities and Exchange Commission filings)
may be incorporated slowly or even ignored. See Stout,
supra, at 653–656; see e.g., In re Merck & Co. Securities
Litigation, 432 F. 3d 261, 263–265 (CA3 2005) (a WallStreet Journal article caused a steep decline in the company’s stock price even though the same information was
contained in an earlier SEC disclosure).
Further, and more importantly, “overwhelming empirical evidence” now suggests that even when markets doincorporate public information, they often fail to do so——————
form is generally accepted; the strong form is not. See ibid.

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accurately. Lev and de Villiers, Stock Price Crashes and10b–5 Damages: A Legal, Economic and Policy Analysis,
47 Stan. L. Rev. 7, 20–21 (1994); see also id., at 21 (“Thatmany share price movements seem unrelated to specificinformation strongly suggests that capital markets are notfundamentally efficient, and that wide deviations fromfundamentals . . . can occur”(footnote omitted)). “Scores”
of “efficiency-defying anomalies”—such as market swings
in the absence of new information and prolonged deviations from underlying asset values—make market efficiency“more contestable than ever.” Langevoort, Taming theAnimal Spirits of the Stock Markets: A Behavioral Approach to Securities Regulation, 97 Nw. U. L. Rev. 135,141 (2002); Dunbar & Heller 476–483. Such anomalies
make it difficult to tell whether, at any given moment, astock’s price accurately reflects its value as indicated by
all publicly available information. In sum, economists
now understand that the price impact Basic assumed
would happen reflexively is actually far from certain evenin “well-developed” markets. Thus, Basic’s claim that“common sense and probability” support a presumption ofreliance rests on shaky footing.
2
The Basic Court also grounded the presumption ofreliance in a second assumption: that “[a]n investor whobuys or sells stock at the price set by the market does so inreliance on the integrity of that price.” 485 U. S., at 247.
In other words, the Court assumed that investors transact
based on the belief that the market price accurately reflects the underlying “ ‘value’ ” of the security. See id., at244 (“ ‘[P]urchasers generally rely on the price of the stock
as a reflection of its value’ ”). The Basic Court appears tohave adopted this assumption about investment behavior
based only on what it believed to be “common sense.” Id.,
at 246. The Court found it “ ‘hard to imagine that there

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ever is a buyer or seller who does not rely on market integrity. Who would knowingly roll the dice in a crooked
crap game?’ ” Id., at 246–247.
The Court’s rather superficial analysis does not withstand scrutiny. It cannot be seriously disputed that agreat many investors do not buy or sell stock based on abelief that the stock’s price accurately reflects its value.
Many investors in fact trade for the opposite reason—that
is, because they think the market has under- or overvalued the stock, and they believe they can profit from thatmispricing. Id., at 256 (opinion of White, J.); see, e.g.,
Macey, The Fraud on the Market Theory: Some Preliminary Issues, 74 Cornell L. Rev. 923, 925 (1989) (The “opposite” of Basic’s assumption appears to be true; someinvestors “attempt to locate undervalued stocks in aneffort to ‘beat the market’ . . . in essence betting that themarket . . . is in fact inefficient”). Indeed, securities
transactions often take place because the transacting
parties disagree on the security’s value. See, e.g., Stout,
Are Stock Markets Costly Casinos? Disagreement, Market Failure, and Securities Regulation, 81 Va. L. Rev.
611, 619 (1995) (“[A]vailable evidence suggests that . . . investor disagreement inspires the lion’s share of equities
transactions”).
Other investors trade for reasons entirely unrelated toprice—for instance, to address changing liquidity needs,
tax concerns, or portfolio balancing requirements. See id.,
at 657–658; see also Cox 1739 (investors may purchase“due to portfolio rebalancing arising from its obeisance toan indexing strategy”). These investment decisions—
made with indifference to price and thus without regard
for price “integrity”—are at odds with Basic’s understanding of what motivates investment decisions. In short,
Basic’s assumption that all investors rely in common on

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THOMAS, J., concurring in judgment“price integrity” is simply wrong.5
The majority tries (but fails) to reconcile Basic’s assumption about investor behavior with the reality thatmany investors do not behave in the way Basic assumed.
It first asserts that Basic rested only on the more modest
view that “ ‘most investors’ ” rely on the integrity of asecurity’s market price. Ante, at 12 (quoting not Basic, but
Amgen Inc. v. Connecticut Retirement Plans & TrustFunds, 568 U. S. ___, ___ (2013) (slip op., at 5) (emphasis
added)). That gloss is difficult to square with Basic’s plain
language: “An investor who buys or sells stock at the priceset by the market does so in reliance on the integrity ofthat price.” Basic, 458 U. S., at 247; see also id., at 246–
247 (“ ‘[I]t is hard to imagine that there ever is a buyer orseller who does not rely on market integrity’ ”). In any
event, neither Basic nor the majority offers anything morethan a judicial hunch as evidence that even “most” investors rely on price integrity.
The majority also suggests that “there is no reason to
suppose” that investors who buy stock they believe to beundervalued are “indifferent to the integrity of market
prices.” Ante, at 12. Such “value investor[s],” according to
the majority, “implicitly rel[y] on the fact that a stock’s
market price will eventually reflect material information”——————
5 The Basic Court’s mistaken intuition about investor behavior appears to involve a category mistake: the Court invoked a hypothesis
meant to describe markets, but then used it “in the one way it is notmeant to be used: as a predictor of the behavior of individual investors.”
Langevoort, Theories, Assumptions, and Securities Regulation: Market
Efficiency Revisited, 140 U. Pa. L. Rev. 851, 895 (1992). The efficient
capital markets hypothesis does not describe “how investors behave; [it]only suggests the consequences of their collective behavior.” Cox 1736.
“Nothing in the hypothesis denies what most popular accounts assume:that much information searching and trading by investors, from institutions on down, is done in the (perhaps erroneous) belief that undervalued or overvalued stocks exist and can systematically be discovered.”Langevoort, Theories, supra, at 895.

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and “presumably tr[y] to estimate how undervalued or
overvalued a particular stock is” by reference to the market price. Ibid. Whether the majority’s unsupported
claims about the thought processes of hypothetical investors are accurate or not, they are surely beside the point.
Whatever else an investor believes about the market, hesimply does not “rely on the integrity of the market price”
if he does not believe that the market price accuratelyreflects public information at the time he transacts. Thatis, an investor cannot claim that a public misstatement
induced his transaction by distorting the market price if
he did not buy at that price while believing that it accurately incorporated that public information. For that sortof investor, Basic’s critical fiction falls apart.
B
Basic’s presumption of reliance also conflicts with ourmore recent cases clarifying Rule 23’s class-certification
requirements. Those cases instruct that “a party seeking
to maintain a class action ‘must affirmatively demonstrate
his compliance’ with Rule 23.” Comcast, 569 U. S., at ___(slip op., at 5) (quoting Wal-Mart, 564 U. S., at ___ (slipop., at 10). To prevail on a motion for class certification, aparty must demonstrate through “evidentiary proof ” that“ ‘questions of law or fact common to class members predominate over any questions affecting only individual
members.’ ” 569 U. S., at ___ (slip op., at 5–6) (quoting
Fed. Rule Civ. Proc. 23(b)(3)).
Basic permits plaintiffs to bypass that requirement ofevidentiary proof. Under Basic, plaintiffs who invoke thepresumption of reliance (by proving its predicates) are
deemed to have met the predominance requirement ofRule 23(b)(3). See ante, at 14; Amgen, supra, at ___ (slipop., at 6) (Basic “facilitates class certification by recognizing a rebuttable presumption of classwide reliance”);
Basic, 485 U. S., at 242, 250 (holding that the District

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Court appropriately certified the class based on the presumption of reliance). But, invoking the Basic presumption does not actually prove that individual questions ofreliance will not overwhelm the common questions in thecase. Basic still requires a showing that the individual
investor bought or sold in reliance on the integrity of themarket price and, crucially, permits defendants to rebut
the presumption by producing evidence that individual
plaintiffs do not meet that description. See id., at 249(“Petitioners . . . could rebut the presumption of relianceas to plaintiffs who would have divested themselves of
their Basic shares without relying on the integrity of themarket”). Thus, by its own terms, Basic entitles defendants to ask each class member whether he traded in reliance on the integrity of the market price. That inquiry,
like the traditional reliance inquiry, is inherently individualized; questions about the trading strategies of individual investors will not generate “ ‘common answers apt todrive the resolution of the litigation,’ ” Wal-Mart Stores,
supra, at ___ (slip op., at 10). See supra, at 8–9; see also
Cox 1736, n. 55 (Basic’s recognition that defendants could
rebut the presumption “by proof the investor would have
traded anyway appears to require individual inquiries intoreliance”).
Basic thus exempts Rule 10b–5 plaintiffs from Rule 23’s
proof requirement. Plaintiffs who invoke the presumptionof reliance are deemed to have shown predominance as amatter of law, even though the resulting rebuttable presumption leaves individualized questions of reliance in thecase and predominance still unproved. Needless to say,that exemption was beyond the Basic Court’s power togrant.6——————
6 The majority suggests that Basic squares with Comcast Corp. v.
Behrend, 569 U. S. ___ (2013), and Wal-Mart Stores, Inc. v. Dukes, 564
U. S. ___ (2011), because it does not “relieve plaintiffs of the burden of164

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CIt would be bad enough if Basic merely provided an endrun around Rule 23. But in practice, the so-called “rebuttable presumption” is largely irrebuttable.
The Basic Court ostensibly afforded defendants anopportunity to rebut the presumption by providing evidence that either aspect of a plaintiff ’s fraud-on-themarket reliance—price impact, or reliance on the integrityof the market price—is missing. 485 U. S., at 248–249. As
it turns out, however, the realities of class-action procedure make rebuttal based on an individual plaintiff ’s lackof reliance virtually impossible. At the class-certification
stage, rebuttal is only directed at the class representatives, which means that counsel only needs to find oneclass member who can withstand the challenge. See
Grundfest, Damages and Reliance Under Section 10(b) of
the Exchange Act, 69 Bus. Lawyer 307, 362 (2014). Afterclass certification, courts have refused to allow defendants
to challenge any plaintiff ’s reliance on the integrity of themarket price prior to a determination on classwide liability. See Brief for Chamber of Commerce of the UnitedStates of America et al. as Amici Curiae 13–14 (collecting
cases rejecting postcertification attempts to rebut individual class members’ reliance on price integrity as not pertinent to classwide liability). One search for rebuttals on
individual-reliance grounds turned up only six cases out of
the thousands of Rule 10b–5 actions brought since Basic.
Grundfest, supra, at 360.7——————
proving . . . predominance” but “rather sets forth what they must prove
to demonstrate such predominance.” Ante, at 14–15. This argument
misses the point. Because Basic offers defendants a chance to rebut thepresumption on individualized grounds, the predicates that Basic sets
forth as sufficient to invoke the presumption do not necessarily prove
predominance.
7 The absence of postcertification rebuttal is likely attributable inpart to the substantial in terrorem settlement pressures brought to bear

165

14

HALLIBURTON CO. v. ERICA P. JOHN FUND, INC.
THOMAS, J., concurring in judgment

The apparent unavailability of this form of rebuttal has
troubling implications. Because the presumption is conclusive in practice with respect to investors’ reliance on
price integrity, even Basic’s watered-down reliance requirement has been effectively eliminated. Once thepresumption attaches, the reliance element is no longer an
obstacle to prevailing on the claim, even though many
class members will not have transacted in reliance on
price integrity, see supra, at 8–9. And without a functional reliance requirement, the “essential element” that
ensures the plaintiff has actually been defrauded, see
Stoneridge, 552 U. S., at 159, Rule 10b–5 becomes the very“ ‘scheme of investor’s insurance’ ” the rebuttable presumption was supposed to prevent. See Basic, supra, at 252(opinion of White, J.).8***
For these reasons, Basic should be overruled in favor of
the straightforward rule that “[r]eliance by the plaintiff
upon the defendant’s deceptive acts”—actual reliance, notthe fictional “fraud-on-the-market” version—“is an essential element of the §10(b) private cause of action.” Stoneridge, 552 U. S., at 159.
——————
by certification. See, e.g., Nagareda, Class Certification in the Age ofAggregate Proof, 84 N. Y. U. L. Rev. 97, 99 (2009) (“With vanishingly
rare exception, class certification sets the litigation on a path toward resolution by way of settlement, not full-fledged testing of the plaintiffs’ caseby trial”); see also Stoneridge Investment Partners, LLC v. ScientificAtlanta, Inc., 552 U. S. 148, 163 (2008) (“[E]xtensive discovery andthe potential for uncertainty and disruption in a lawsuit allow plaintiffs
with weak claims to extort settlements from innocent companies”).
8 Of course, today’s decision makes clear that a defendant may rebut
the presumption by producing evidence that the misstatement at issue
failed to affect the market price of the security, see ante, at 17–22. But
both parts of Basic’s version of reliance are key to its fiction that an
investor has “indirectly” relied on the misstatement; the unavailabilityof rebuttal with respect to one of those parts still functionally removes
reliance as an element of proof.

166

Cite as: 573 U. S. ____ (2014)15

THOMAS, J., concurring in judgment

III
Principles of stare decisis do not compel us to save
Basic’s muddled logic and armchair economics. We have
not hesitated to overrule decisions when they are “unworkable or are badly reasoned,” Payne v. Tennessee, 501
U. S. 808, 827 (1991); when “the theoretical underpinningsof those decisions are called into serious question,” StateOil Co. v. Khan, 522 U. S. 3, 21 (1997); when the decisions
have become “irreconcilable” with intervening developments in “competing legal doctrines or policies,” Patterson
v. McLean Credit Union, 491 U. S. 164, 173 (1989); or
when they are otherwise “a positive detriment to coherence and consistency in the law,” ibid. Just one of thesecircumstances can justify our correction of bad precedent;
Basic checks all the boxes.
In support of its decision to preserve Basic, the majority
contends that stare decisis “has ‘special force’ ‘in respect tostatutory interpretation’ because ‘Congress remains free toalter what we have done.’ ” Ante, at 12 (quoting John R.
Sand & Gravel Co. v. United States, 552 U. S. 130, 139(2008); some internal quotation marks omitted). But
Basic, of course, has nothing to do with statutory interpretation. The case concerned a judge-made evidentiary
presumption for a judge-made element of the implied
10b�5 private cause of action, itself “a judicial constructthat Congress did not enact in the text of the relevant
statutes.” Stoneridge, supra, at 164. We have not afforded
stare decisis “special force” outside the context of statutory interpretation, see Michigan v. Bay Mills IndianCommunity, 572 U. S. ___, ___, n. 6 (2014) (THOMAS, J.
dissenting) (slip op., at 15, n. 6 and for good reason. In
statutory cases, it is perhaps plausible that Congress
watches over its enactments and will step in to fix our
mistakes, so we may leave to Congress the judgment
whether the interpretive question is better left “ ‘settled’ ”
or “ ‘settled right,’ ” Square D Co. v. Niagara Frontier

167

16

HALLIBURTON CO. v. ERICA P. JOHN FUND, INC.
THOMAS, J., concurring in judgment

Tariff Bureau, Inc., 476 U. S. 409, 424 (1986). But thisrationale is untenable when it comes to judge-made law
like “implied” private causes of action, which we retain aduty to superintend. See, e.g., Exxon Shipping Co. v.
Baker, 554 U. S. 471, 507 (2008) (“[T]he judiciary [cannot]
wash its hands of a problem it created . . . simply by calling [the judicial doctrine] legislative”). Thus, when we err
in areas of judge-made law, we ought to presume that
Congress expects us to correct our own mistakes—not theother way around. That duty is especially clear in theRule 10b–5 context, where we have said that “[t]he federal
courts have accepted and exercised the principal responsibility for the continuing elaboration of the scope of the10b–5 right and the definition of the duties it imposes.”Musick, Peeler & Garrett v. Employers Ins. of Wausau, 508
U. S. 286, 292 (1993).
Basic’s presumption of reliance remains our mistake tocorrect. Since Basic, Congress has enacted two major
securities laws: the Private Securities Litigation ReformAct of 1995 (PSLRA), 109 Stat. 737, and the Securities
Litigation Uniform Standards Act of 1998 (SLUSA), 112
Stat. 3227. The PSLRA “sought to combat perceived
abuses in securities litigation,” ante, at 15, and SLUSA
prevented plaintiffs from avoiding the PSLRA’s restrictions by bringing class actions in state court, ibid.
Neither of these Acts touched the reliance element of theimplied Rule 10b–5 private cause of action or the Basicpresumption.
Contrary to respondent’s argument (the majority wisely
skips this next line of defense), we cannot draw from
Congress’ silence on this matter an inference that Congress approved of Basic. To begin with, it is inappropriate
to give weight to “Congress’ unenacted opinion” whenconstruing judge-made doctrines, because doing so allows
the Court to create law and then “effectively codif[y]” it“based only on Congress’ failure to address it.” Bay Mills,

168

Cite as: 573 U. S. ____ (2014)17

THOMAS, J., concurring in judgmentsupra, at ___ (THOMAS, J., dissenting) (slip op., at 14).
Our Constitution, however, demands that laws be passed
by Congress and signed by the President. U. S. Const.,
Art. I, §7. Adherence to Basic based on congressional
inaction would invert that requirement by insulating error
from correction merely because Congress failed to pass alaw on the subject. Cf. Patterson, supra, at 175, n. 1(“Congressional inaction cannot amend a duly enacted
statute”).
At any rate, arguments from legislative inaction are
speculative at best. “[I]t is ‘ “impossible to assert with any
degree of assurance that congressional failure to act represents” affirmative congressional approval of ’ one of thisCourt’s decisions.” Bay Mills, supra, at ___ (THOMAS, J.,dissenting) (slip op., at 13) (quoting Patterson, supra, at
175, n. 1). “ ‘Congressional inaction lacks persuasive
significance’ ” because it is indeterminate; “ ‘several equally
tenable inferences may be drawn from such inaction.’ ”
Central Bank of Denver, N. A. v. First Interstate Bank of
Denver, N. A., 511 U. S. 164, 187 (1994) (quoting Pension
Benefit Guaranty Corporation v. LTV Corp., 496 U. S. 633,
650 (1990)). Therefore, “[i]t does not follow . . . that Congress’ failure to overturn a . . . precedent is reason for thisCourt to adhere to it.” Patterson, supra, at 175, n. 1.
That is especially true here, because Congress passed alaw to tell us not to draw any inference from its inaction.
The PSLRA expressly states that “[n]othing in this Act . . .
shall be deemed to create or ratify any implied privateright of action.” Notes following 15 U. S. C. §78j–1, p. 430.
If the Act did not ratify even the Rule 10b–5 private causeof action, it cannot be read to ratify sub silentio the presumption of reliance this Court affixed to that action.
Further, the PSLRA and SLUSA operate to curtail abusesof various private causes of action under our securities
laws—hardly an indication that Congress approved of
Basic’s expansion of the 10b–5 private cause of action.

169

18

HALLIBURTON CO. v. ERICA P. JOHN FUND, INC.
THOMAS, J., concurring in judgment

Congress’ failure to overturn Basic does not permit us to“place on the shoulders of Congress the burden of the
Court’s own error.” Girouard v. United States, 328 U. S.
61, 70 (1946).
***
Basic took an implied cause of action and grafted on apolicy-driven presumption of reliance based on nascenteconomic theory and personal intuitions about investment
behavior. The result was an unrecognizably broad causeof action ready made for class certification. Time andexperience have pointed up the error of that decision,
making it all too clear that the Court’s attempt to revise
securities law to fit the alleged “new realities of financial
markets” should have been left to Congress. 485 U. S., at
255 (opinion of White, J.).

170

金融商品取引法研究会名簿（平成 26 年 11 月 26 日現在）

会
長
副 会 長
委
員
〃
〃
〃
〃
〃
〃
〃
〃
〃
〃
〃
〃
〃
幹
事

神 田 秀 樹前 田 雅 弘青 木 浩 子
飯 田 秀 総太 田洋
加 藤 貴 仁川 口 恭 弘神 作 裕 之黒 沼 悦 郎後 藤
元
中 東 正 文中 村聡
藤 田 友 敬松 尾 健 一松 尾 直 彦山 田 剛 志萬 澤 陽 子

東京大学大学院法学政治学研究科教授
京都大学大学院法学研究科教授
千葉大学大学院専門法務研究科教授
神戸大学大学院法学研究科准教授
西村あさひ法律事務所パートナー・弁護士
東京大学大学院法学政治学研究科准教授
同志社大学大学院法学研究科教授
東京大学大学院法学政治学研究科教授
早稲田大学大学院法務研究科教授
東京大学大学院法学政治学研究科准教授
名古屋大学大学院法学研究科教授
森・濱田松本法律事務所パートナー・弁護士
東京大学大学院法学政治学研究科教授
大阪大学大学院法学研究科准教授
東京大学大学院法学政治学研究科客員教授・弁護士
成城大学法学部教授
専修大学法学部講師・当研究所客員研究員

オブザーバー 田 原 泰 雄〃
永 井 智 亮金融庁総務企画局市場課長
野村證券常務執行役員
兼チーフ・リーガル・オフィサー
大和証券グループ本社執行役員経営企画部長
ＳＭＢＣ日興証券法務部長
みずほ証券法務部長
三菱ＵＦＪモルガン・スタンレー証券法務部長
日本証券業協会専務執行役
日本証券業協会執行役
日本証券業協会自主規制本部副本部長
東京証券取引所総務部法務グループ課長

〃
〃
〃
〃
〃
〃
〃
〃

荻
鎌
金
田
平
山
三
高

野
塚
井
島
田
内
森
良

明
正
仁
浩
公
公

彦
人
雄
毅
一
明
肇
美紀子

研 究 所 増 井 喜一郎
〃
大 前
忠
〃
安 田 賢 治日本証券経済研究所理事長
日本証券経済研究所常務理事
日本証券経済研究所事務局長
（敬称略）

171

［参考］ 既に公表した「金融商品取引法研究会（証券取引法研究会）
研究記録」

第１号「裁判外紛争処理制度の構築と問題点」
報告者 森田章同志社大学教授

2003 年 11月

第２号「システム障害と損失補償問題」
報告者 山下友信東京大学教授

2004 年１月

第３号「会社法の大改正と証券規制への影響
報告者 前田雅弘京都大学教授

2004 年３月

第４号「証券化の進展に伴う諸問題（倒産隔離の明確化等）」 2004 年６月
報告者 浜田道代名古屋大学教授
第５号「EU における資本市場法の統合の動向―投資商品、証券業務の範囲を中心として―」

報告者

2005 年 7 月

神作裕之東京大学教授

第６号「近時の企業情報開示を巡る課題―実効性確保の観点を中心に―」報告者 山田剛志新潟大学助教授

2005 年７月

第７号「プロ・アマ投資者の区分―金融商品・2005 年９月

販売方法等の変化に伴うリテール規制の再編―」

報告者

青木浩子千葉大学助教授

第８号「目論見書制度の改革」
報告者 黒沼悦郎早稲田大学教授

2005 年 11月

第９号「投資サービス法（仮称）について」2005 年 11月
報告者 三井秀範金融庁総務企画局市場課長
松尾直彦金融庁総務企画局
投資サービス法（仮称）法令準備室長
第 10 号「委任状勧誘に関する実務上の諸問題―委任状争奪戦（proxy ﬁght）の文脈を中心に―」

報告者

2005 年 11月

太田洋 西村ときわ法律事務所パートナー・弁護士

第 11 号「集団投資スキームに関する規制について
2005 年 12月―組合型ファンドを中心に―」報告者 中村聡 森・濱田松本法律事務所パートナー･弁護士
第 12 号「証券仲介業」
報告者 川口恭弘同志社大学教授

172

2006 年３月

第 13 号「敵対的買収に関する法規制」
報告者 中東正文名古屋大学教授

2006 年５月

第 14 号「証券アナリスト規制と強制情報開示・不公正取引規制」 2006 年７月
報告者 戸田暁京都大学助教授
第 15 号「新会社法のもとでの株式買取請求権制度」
報告者 藤田友敬東京大学教授

2006 年９月

第 16 号「証券取引法改正に係る政令等について」2006 年 12月（ＴＯＢ、大量保有報告関係、内部統制報告関係）
報告者 池田唯一金融庁総務企画局企業開示課長
第 17 号「間接保有証券に関するユニドロア条約策定作業の状況」 2007 年５月
報告者 神田秀樹 東京大学大学院法学政治学研究科教授
第 18 号「金融商品取引法の政令・内閣府令について」2007 年６月
報告者 三井秀範 金融庁総務企画局市場課長
第 19 号「特定投資家・一般投資家について」2007 年９月
報告者 青木浩子 千葉大学大学院専門法務研究科教授
第 20 号「金融商品取引所について」2007 年 10月
報告者 前田雅弘 京都大学大学院法学研究科教授
第 21 号「不公正取引について−村上ファンド事件を中心に−」2008 年１月
報告者 太田 洋 西村あさひ法律事務所パートナー・弁護士
第 22 号「大量保有報告制度」
報告者 神作裕之

2008 年３月
東京大学大学院法学政治学研究科教授

第 23 号「開示制度（Ⅰ）―企業再編成に係る開示制度および2008 年４月
集団投資スキーム持分等の開示制度―」
報告者 川口恭弘 同志社大学大学院法学研究科教授
第 24 号「開示制度（Ⅱ）―確認書、内部統制報告書、四半期報告書―」 2008 年７月
報告者 戸田 暁 京都大学大学院法学研究科准教授
第 25 号「有価証券の範囲」
報告者 藤田友敬

2008 年７月
東京大学大学院法学政治学研究科教授

第 26 号「民事責任規定・エンフォースメント」
2008 年 10月
報告者 近藤光男 神戸大学大学院法学研究科教授
第 27 号「金融機関による説明義務・適合性の原則と金融商品販売法」2009 年１月
報告者 山田剛志 新潟大学大学院実務法学研究科准教授
第 28 号「集団投資スキーム（ファンド）規制」
2009 年３月
報告者 中村聡 森・濱田松本法律事務所パートナー・弁護士
173

第 29 号「金融商品取引業の業規制」
2009 年４月
報告者 黒沼悦郎 早稲田大学大学院法務研究科教授
第 30 号「公開買付け制度」
報告者 中東正文2009 年７月
名古屋大学大学院法学研究科教授

第 31 号「最近の金融商品取引法の改正について」2011 年３月
報告者 藤本拓資 金融庁総務企画局市場課長
第 32 号「金融商品取引業における利益相反―利益相反管理体制の整備業務を中心として―」

報告者

神作裕之

2011 年６月

東京大学大学院法学政治学研究科教授

第 33 号「顧客との個別の取引条件における特別の利益提供に関する問題」2011 年９月
報告者 青木浩子 千葉大学大学院専門法務研究科教授
松本譲治 ＳＭＢＣ日興証券 法務部長
第 34 号「ライツ・オファリングの円滑な利用に向けた制度整備と課題」2011 年 11月
報告者 前田雅弘 京都大学大学院法学研究科教授
第 35 号「公開買付規制を巡る近時の諸問題」
2012 年２月
報告者 太田 洋 西村あさひ法律事務所弁護士・NY州弁護士
第 36 号「格付会社への規制」
報告者 山田剛志

成城大学法学部教授

2012 年６月

第 37 号「金商法第６章の不公正取引規制の体系」
2012 年７月
報告者 松尾直彦 東京大学大学院法学政治学研究科客員教授・西村あさひ法律事務所弁護士
第 38 号「キャッシュ・アウト法制」
2012 年 10月
報告者 中東正文 名古屋大学大学院法学研究科教授
第 39 号「デリバティブに関する規制」
2012 年 11月
報告者 神田秀樹 東京大学大学院法学政治学研究科教授
第 40 号「米国 JOBS 法による証券規制の変革」
2013 年１月
報告者 中村聡 森・濱田松本法律事務所パートナー・弁護士
第 41 号「金融商品取引法の役員の責任と会社法の役員の責任 2013 年３月―虚偽記載をめぐる役員の責任を中心に―」報告者 近藤光男 神戸大学大学院法学研究科教授
第 42 号「ドッド＝フランク法における信用リスクの保持ルールについて」 2013 年４月
報告者 黒沼悦郎 早稲田大学大学院法務研究科教授
第 43 号「相場操縦の規制」
報告者 藤田友敬

2013 年８月
東京大学大学院法学政治学研究科教授

174

第 44 号「法人関係情報」
2013 年 10月
報告者 川口恭弘 同志社大学大学院法学研究科教授
平田公一 日本証券業協会常務執行役
第 45 号「最近の金融商品取引法の改正について」2014 年６月
報告者 藤本拓資 金融庁総務企画局企画課長
第 46 号「リテール顧客向けデリバティブ関連商品販売における民事責任 2014 年９月―「新規な説明義務」を中心として―」報告者 青木浩子 千葉大学大学院専門法務研究科教授
第 47 号「投資者保護基金制度」
報告者 神田秀樹

2014 年 10月
東京大学大学院法学政治学研究科教授

175

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金融商品取引法研究会研究記録

第 48 号

市場に対する詐欺に関する米国判例の動向について平成 27 年１月 27 日
定価（本体 500 円＋税）
編 者
発行者

金 融 商 品 取 引 法 研 究 会
公益財団法人 日本証券経済研究所

東京都中央区日本橋茅場町 1-5-8

東京証券会館内
電話〒 103-0025

03（3669）0737 代表

URL: http://www.jsri.or.jp

ISBN978-4-89032-664-8 C3032 ¥500E