Ask HN: How to identify PE owned businesses

As a side project I've played with the idea of having some kind of a directory where you can look up which local businesses, Drs etc are owned by a private equity group. Not that those entities equal worse service necessarily, but it'd still be good to know who is behind.

While I didn't have the time to build something, I was still wondering if there are resources available starters that one could use? For companies it's somewhat easy (and part of the research before joining one), but it gets more tricky for Drs offices etc.