NATIONAL BUREAU OF ECONOMIC RESEARCH
NBER Working Papers and Publications
|January 1999||The Profits to Insider Trading: A Performance-Evaluation Perspective|
with Andrew Metrick, Richard Zeckhauser: w6913
This paper estimates the profits to insiders when they trade their company's stock. We construct a rolling purchase portfolio' that holds all shares purchased by insiders over the previous year and an analogous sale portfolio' that holds all shares sold by insiders over the previous year. We then analyze the returns to these value-weighted portfolios using performance-evaluation methods. This approach allows us to study the returns to insider transactions beginning on the day after their execution, and is free of the statistical difficulties that plague event studies on long-horizon returns. Using a comprehensive sample of reported insider transactions from 1975 - 1996, we find that the purchase portfolio earns abnormal returns of about 40 basis points per month, with about one-sixth...