Steve Ballmer said today that Microsoft will acquire 20 companies a year for the next 5 years ranging from $50 Million to $1 Billion. In fact, Microsoft has been very active on the acquisition front for the past several years. Wikipedia keeps a fairly accurate and up to date list of Microsoft acquisitions.

Todd Bishop at the Seattle Post Intelligencer put together this graph of recent acquisitions. Note that both the number of deals and dollar value is going up. In fact, this year will mark the first time in Microsoft's history where more was spent on acquisitions than on internal R&D. Of course, one acquisition, aQuantive, accounts for about $6 Billion of the total acquisition spend. The aQuantive deal is not included in the chart above.

Venture Beat reported that Microsoft has only acquired 4 companies this year. The numbers vary by fiscal year and calendar year. Just for the record it is currently 13 companies this calendar year and there is still a lot of time left. Here is a list from Wikipedia of the 13 companies;

Steve mentioned that the sweet spot for acquisitions is around $100 million, but Microsoft will acquire small companies of 5 or 10 people, all the way up to huge acquisitions of thousands of people and billions of dollars. Take a look at the list above...it is hard to generalize in terms of size, technology, or dollar vlaue.

Steve also mentioned that Microsoft will make acquisitions of "open source" based companies or products built with Java. Microsoft will not let technology decisions get in the way of acquisitions that make sense.

Another example of Microsoft's willingness to work with companies not wed to the Microsoft platform is the recent partnership announcements with Atlassian and Newsgator.