Document ID: ./input/supremecourt_opinions/opinions/20pdf/20-222_2c83.pdf
Page Number: 10

Cite as:  594 U. S. ____ (2021) 

7 

Opinion of the Court 

of thumb, “a more-general statement will affect a security’s
price less than a more-specific statement on the same ques-
tion.”  Brief for Respondents 15; see Tr. of Oral Arg. 6–7, 59, 
79.  The parties further agree that courts may consider ex-
pert  testimony  and  use  their  common  sense  in  assessing
whether  a  generic  misrepresentation  had  a  price  impact.
See Tr. of Oral Arg. 12, 64.  And they likewise agree that 
courts may assess the generic nature of a misrepresentation
at class certification even though it also may be relevant to
materiality, which Amgen reserves for the merits.  See id., 
at 23, 65. 

We share the parties’ view.  In assessing price impact at 
class certification, courts “ ‘should be open to all probative
evidence on that question—qualitative as well as quantita-
tive—aided by a good dose of common sense.’ ”  In re Allstate 
Corp. Securities Litig., 966 F. 3d 595, 613, n. 6 (CA7 2020) 
(quoting Langevoort, Judgment Day for Fraud-on-the-Mar-
ket: Reflection on Amgen and the Second Coming of Halli-
burton,  57  Ariz.  L. Rev.  37,  56  (2015);  emphasis  added). 
That is so regardless whether the evidence is also relevant 
to a merits question like materiality.  As we have repeat-
edly explained, a court has an obligation before certifying a 
class  to  “determin[e]  that  Rule 23  is  satisfied,  even  when 
that  requires  inquiry  into  the  merits.”  Comcast  Corp.  v. 
Behrend, 569 U. S. 27, 35 (2013); see Wal-Mart Stores, Inc. 
v. Dukes, 564 U. S. 338, 351, and n. 6 (2011).  And under 
Halliburton  II,  a  court  cannot  conclude  that  Rule  23’s  re-
quirements  are  satisfied  without  considering  all  evidence 
relevant to price impact.  See 573 U. S., at 284.2 

—————— 

2 We recognize that materiality and price impact are overlapping con-
cepts and that the evidence relevant to one will almost always be rele-
vant to the other.  But “a district court may not use the overlap to refuse
to consider the evidence.”  In re Allstate, 966 F. 3d, at 608.  Instead, the 
district  court  must  use  the  evidence  to  decide  the  price  impact  issue 
“while resisting the temptation to draw what may be obvious inferences 
for the closely related issues that must be left for the merits, including