Most securities fraud class actions allege that the defendant company lied to the market to maintain a higher stock price than what would have prevailed if investors had known the truth. But there is no general duty requiring disclosure of information simply because it is material. Accordingly, some scholars argue that to state a claim for fraud, a misrepresentation must cause stock price to increase absent a duty to speak. The implications of this debate extend beyond the mere definition of fraud. A price-inflation requirement would imply minimal liability as measured by the price increase (if any) caused by an alleged misrepresentation. In contrast, the price-maintenance theory seems to imply liability for the difference between the price paid and the price prevailing after corrective disclosure. After analyzing these two possibilities, this Article considers a third possibility: One might measure the loss by the difference between the price paid and the price that would have been paid if the market had known the truth. The Supreme Court has ruled that defendant companies must be permitted to show that the effects of corrective disclosure come from sources other than fraud. But losses other than from such mispricing are almost always derivative and should give rise to recovery by the company. Moreover, the rule is that a class action for damages must be superior to other modes of resolving the dispute. It follows that any portion of a claim that can be litigated as a derivative action must be so litigated. And to the extent that the subject company recovers in the derivative action, damages will be mitigated in any subsequent class action.