Image source: SunEdison.

What: Shares of yieldco TerraForm Power Inc. (NASDAQ:TERP) were up about 14% near the end of Friday trading on Wall Street after getting another vote of approval from an investor.

So what: Appaloosa Management, a hedge fund run by billionaire David Tepper, has increased  its stake in TerraForm Power from 9.5% at the end of 2015 to 10.88%. Tepper has been prodding for changes at the SunEdison yieldco since late last year, when he bought a large stake in it. Earlier this week, he pushed for the removal of executives who also had a relationship with SunEdison. Shortly thereafter, CEO Brian Wuebbels, who was SunEdison's former CFO, resigned as CEO of TerraForm Power.  

Now what: Tepper's activism is clearly having an effect on TerraForm Power, and his purchase of additional shares is a further vote of confidence in the company's long-term value. If TerraForm Power can gain its independence and begin making more prudent acquisitions, it could be a great dividend stock for investors.

There are still a lot of questions to be answered, especially if sponsor SunEdison goes bankrupt, but having an investor with a strong record like Tepper on your side can't be a bad thing.