2006 proved to be a banner year for global mergers & acquisitions with $3.79 trillion worth of deals, which even surpassed the deals made during the height of the dot com boom in 2000. As you may have noticed, when a merger or acquisition is announced, the stock of the company getting acquired usually jumps up and closes the day at a price very close to the acquisition price but often a little lower. For example when private equity firm Genstar Capital announced the acquisition of International Aluminium Corp (IAL) yesterday, the stock jumped up more than 4% to close the day at $52.08. This is almost a dollar less than the acquisition price of $53 per share in cash that Genstar is offering. Here are a few reasons why this occurs.