To invoke the fraud-on-the-market presumption of reliance under Basic, Inc. v. Levinson (1988) 108 S.Ct. 978, the plaintiff must  prove: (1) that the alleged misrepresentation was publicly known; (2) that it was material; (3) that the stock traded in an efficient market; and (4) that the plaintiff traded the stock between the time the misrepresentation was made and when the truth was revealed. The defendant can then rebut the presumption by any evidence that severs the link between the misrepresentation and plaintiff’s decision to trade or the price at which the trade occurred.  Here, plaintiffs claimed that Goldman had maintained an inflated price for its stock by continually misrepresenting that it had controls in place to prevent conflicts of interest and that it always put its customers’ interest first.  The more generic the misrepresentation, the less it is likely to affect the stock price.  Also, the generic nature of the misrepresentation makes it more difficult to show that a later price drop was due to disclosure of the true facts that were generically misrepresented.  The defendant bears the burden of proof of lack of price impact, but it is unlikely to matter much because the burden of proof affects the outcome only when the evidence is in equipoise, which rarely happens.