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Power And Statistical Significance In Securities Fraud Litigation, Jill E. Fisch, Jonah B. Gelbach
Power And Statistical Significance In Securities Fraud Litigation, Jill E. Fisch, Jonah B. Gelbach
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Event studies, a half-century-old approach to measuring the effect of events on stock prices, are now ubiquitous in securities fraud litigation. In determining whether the event study demonstrates a price effect, expert witnesses typically base their conclusion on whether the results are statistically significant at the 95% confidence level, a threshold that is drawn from the academic literature. As a positive matter, this represents a disconnect with legal standards of proof. As a normative matter, it may reduce enforcement of fraud claims because litigation event studies typically involve quite low statistical power even for large-scale frauds.
This paper, written for …
The Logic And Limits Of Event Studies In Securities Fraud Litigation, Jill E. Fisch, Jonah B. Gelbach, Jonathan Klick
The Logic And Limits Of Event Studies In Securities Fraud Litigation, Jill E. Fisch, Jonah B. Gelbach, Jonathan Klick
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Event studies have become increasingly important in securities fraud litigation after the Supreme Court’s decision in Halliburton II. Litigants have used event study methodology, which empirically analyzes the relationship between the disclosure of corporate information and the issuer’s stock price, to provide evidence in the evaluation of key elements of federal securities fraud, including materiality, reliance, causation, and damages. As the use of event studies grows and they increasingly serve a gatekeeping function in determining whether litigation will proceed beyond a preliminary stage, it will be critical for courts to use them correctly.
This Article explores an array of …
Material Facts In The Debate Over Twombly And Iqbal, Jonah B. Gelbach
Material Facts In The Debate Over Twombly And Iqbal, Jonah B. Gelbach
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This paper presents empirical evidence concerning the adjudication of defendant-filed summary judgment motions from nearly 2,000 randomly selected employment discrimination and contracts cases to try to assess Twombly and Iqbal’s performance in filtering cases according to merit. I first explain how such data might be helpful in such an assessment, taking into account the possibility that parties’ behavior might have changed following Twombly and Iqbal.
I then report results indicating that even using this large collection of data -- the most comprehensive data assembled to date to address this question -- we cannot tell whether “TwIqbal” …