Ask HN: Sources for acquisition data?

I was recently thinking about an old YC blog post that reviewed trends in YC applications over several years (http://blog.ycombinator.com/the-startup-zeitgeist/). I'm interested in performing a similar analysis on startups that have been acquired in the last few years (not necessarily by tech companies). I assumed there would already be something like this out there but haven't found anything that digs deeper than a handful of big players for a relatively short time period.

Does anybody know of any reliable sources of acquisition data?