Comcast bids on Disney. Cingular buys AT&T Wireless. North Fork acquires Greenpoint. Holy merger mania!

Two professors from Wharton and Stanford suggest that mergers -- and the accompanying mania -- may result from overconfidence. Instead of contending that mergers and acquisitions stem from senior leaders' empire-building inclinations -- a stance many skeptics take -- Geoffrey Tate and Ulrike Malmendier offer that instead of putting their own interests ahead of shareholders' -- those leaders just might not have an accurate sense of their own abilities, as well as their companies' prospects.