The discrepancy is caused by the way the two firms calculate the numbers. Altman Weil calculates mergers when they are announced, while Hildebrandt, which just completed its own merger as of January 1, counts them upon their completion. So, taking the Hogan Lovells merger as an example, Altman Weil calculated it into the mix for 2009 while Hildebrandt won’t count it until this year’s report.
A more accurate way to relay the information would be to say that the number of announced mergers was down in 2009, while the number of completed mergers was up.