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4  GOLDMAN SACHS GROUP, INC. v. ARKANSAS TEACHER 

RETIREMENT SYSTEM 
Opinion of the Court 

requires  that  “questions  of  law  or  fact  common  to  class 
members  predominate”  over  individualized  issues.    Fed. 
Rule  Civ.  Proc.  23(b)(3).  Indeed,  without  the  Basic  pre-
sumption, individualized issues of reliance ordinarily would 
defeat predominance and “preclude certification” of a secu-
rities-fraud class action.  Amgen, 568 U. S., at 462–463; see 
Halliburton II, 573 U. S., at 281–282. 

As a result, class-action plaintiffs must prove the Basic 
prerequisites before class certification—with one exception. 
In  Amgen,  we  held  that  materiality  should  be  left  to  the
merits stage because it does not bear on Rule 23’s predomi-
nance requirement.  568 U. S., at 466–468.  The remaining 
Basic prerequisites—publicity, market efficiency, and mar-
ket  timing—“must  be  satisfied”  by  plaintiffs  “before  class 
certification.”  Halliburton II, 573 U. S., at 276. 

Satisfying those prerequisites, however, does not guaran-
tee class certification.  We held in Halliburton II that de-
fendants may rebut the Basic presumption at class certifi-
cation  by  showing  “that  an  alleged  misrepresentation  did 
not  actually  affect  the  market  price  of  the  stock.”    Id.,  at 
284.  If  a  misrepresentation  had  no  price  impact,  then 
Basic’s fundamental premise “completely collapses, render-
ing class certification inappropriate.”  Id., at 283. 

B 
Respondents here—whom we’ll call Plaintiffs—are Gold-
man shareholders.  They brought this securities-fraud class 
action  against  Goldman  in  the  Southern  District  of  New
York, alleging violations of §10(b) and Rule 10b–5.

The specific theory of securities fraud that Plaintiffs al-
lege is known as inflation maintenance.  Under this theory,
a misrepresentation causes a stock price “to remain inflated 
by  preventing  preexisting  inflation  from  dissipating  from
Investor  Group  v. 
FindWhat 
the  stock  price.”