Are stock prices showing mean reversion?

I know stocks are supposed to follow a random walk.  And they pretty much have.  At least over short run (days, weeks, months, and years), if not over the long run (10-20+ years).

But recently--say the last six months or so--doesn't there seem to be a lot more regression to the mean in short-run price movements?  Are hedge funds making a killing by buying low and selling high?

This is just armchair speculation.  I haven't done any unit root tests.  So maybe I'm all wrong about this.