Not all insider sales are the same. In the study reported here, a variable for shares traded as a percentage of insiders' holdings was used to separate information-driven sales from sales driven by liquidity or risk-reduction needs. In the insider trades from 1987 through 2002, only large sales that also accounted for large percentages of insiders' holdings predicted significantly negative future abnormal returns. Small sales that accounted for small percentages of shares owned not only did not predict poor performance but were correlated with significantly positive abnormal returns. The percentage of shares owned by insiders is also useful for predicting future returns following insider purchases.
Fundamental Analysis (Sector, Industry, Company) and the Valuation of Individual Equity Securities