This dissertation consists of two chapters. The first chapter shows that the measurement errors in betas for stocks induce corresponding measurement errors in alphas and a spurious negative covariance between the estimated betas and alphas across stocks. This negative covariance between the...

This dissertation consists of two essays. The first essay develops a new methodology for estimating the probability of informed trading from the observed quotes and depths, by extending the Copeland and Galai (1983) model. This measure (PROBINF) can be computed for each quote and it represents...