In the 1980s, the average first-day return on initial public offerings (IPOs) was 7%. The average first-day return doubled to almost 15% during 1990-1998, before jumping to 65% during the internet bubble years of 1999-2000. Part of the increase can be attributed to changes in the risk...

Defenders of market efficiency argue that anomalies involving long-term abnormal returns are not robust to alternative methodologies. We argue that because various methodologies use different weighting schemes, the magnitude of abnormal returns should differ, and in a predictable manner. Three...