Securities litigation, most often brought under Rule 10b-5, targets material misstatements or omissions made in connection with the purchase or sale of securities. Its elements read like fraud with capital-markets machinery bolted on: a material misrepresentation or omission, scienter, a connection to a securities transaction, reliance, economic loss, and loss causation. The reliance element is eased for public-market claims by the fraud-on-the-market presumption, which assumes an efficient market baked the misstatement into the stock price -- a presumption defendants attack at class certification with price-impact evidence.

Congress layered heightened procedural hurdles onto these cases through the Private Securities Litigation Reform Act. Plaintiffs must plead falsity and a strong inference of scienter with particularity, discovery is automatically stayed while a motion to dismiss is pending, and a lead-plaintiff process selects who steers the class. Loss causation -- linking the corrective disclosure that revealed the truth to the price decline -- becomes a distinct battleground separating a stock drop caused by fraud from one caused by ordinary market forces. Because these are almost always class actions, certification and the size of the affected class dominate exposure and settlement.

Two chokepoints govern these cases: the PSLRA motion to dismiss, where the strong-inference-of-scienter standard ends many suits before discovery, and class certification, where the fraud-on-the-market presumption and price-impact rebuttal decide whether classwide damages are even possible. The automatic discovery stay makes the pleading a high-variance, all-or-nothing bet. Once a class is certified, aggregate damages balloon so quickly that settlement becomes nearly inevitable, so the real negotiation is over certification odds and loss-causation strength.