Holding: The time for a plaintiff to file a federal securities fraud lawsuit begins to run as soon as a plaintiff discovers (or should have discovered) the facts showing a violation of the Securities Exchange Act. A false statement affecting stock prices is not enough to violate the securities law; the defendant must know that the statement was false. As a result, the time to sue does not start to run simply because the plaintiff knows that the statement is false; the time runs only once the plaintiff discovers that the defendant knew that the statement was false.
Judgment: Affirmed, 9-0, in an opinion by Justice Stephen Breyer on April 27, 2010. Justice Stevens filed an opinion concurring in part and concurring in the judgment. Justice Scalia filed a second opinion concurring in part and concurring in the judgment, in which Justice Thomas joined.