On February 1, 2008, Microsoft offered $43.7billion for Yahoo. This offer was a milestone in the battle between Microsoft and Google to control the Internet search industry. The announcement accompanied a substantial decrease in Microsoft's stock price. Investors apparently considered the bid too high and doubted Microsoft's ability to create value with Yahoo's assets (the announcement combined returns implied a total value destruction of $13.29billion). Using the abnormal returns pattern of industry firms and customers, this article examines the sources of overbidding. Our analyses indicate that Microsoft's aggressive move is rooted in its rivalry with Google, but the personality traits of the involved CEOs might explain also a portion of the overbidding.

Knowledge gleaned from previous acquisitions may confer valuation expertise and other benefits. But numerous acquisitions also entail costs, due to problems of incorporating diverse units into an ever larger firm. Such benefits and costs are not directly observable from outside the firm. This article proposes a simple model to infer their relative importance, using the time between successive deals. The data requirements are minimal and allow the use of all mergers and acquisitions during 1992–2009 (more than 300,000 deals). The results provide evidence of learning gains through repetitive acquisitions, especially under CEO continuity and when successive deals are more similar.