There's a terrific article in McKinsey Quarterly about how so many acquisitions often fail to deliver on anticipated synergies because the integration of technology and operations wasn't given adequate consideration during the due diligence stage.

One of the main reasons for the disregard for technology and operations integration is that executives from the two functions (sometimes operated as one) often aren't included in the due diligence process, as noted in the McKinsey article. In McKinsey's work on post-merger management, it has found that 50 to 60 percent of the deals that were expected to yield synergies are "strongly" related to IT but that most IT issues weren't fully addressed during the due diligence or the early stages of post-merger planning.