Coleman’s hedge fund, Tiger Global Management, the top performing hedge fund of 2011, bought shares of Groupon (GRPN) in the third quarter. Tiger Global, like other hedge funds, reported its holdings as of the end of September on Wednesday night. Other new investments for Coleman were ratings agency Moodys (MCO) and search company Yahoo (YHOO).

The Groupon investment is relatively small for the fund, just $6 million, but it’s still notable because it comes at a time when other investors are throwing in the towel on the deals company. Groupon’s shares are down 85% so far this year to a recent $2.73. Many are wondering if the company can survive.

So far it’s likely been a loser for Coleman as well. Recently, Groupon’s stock lost a third of its value in one day after the company reported that its sales had dropped significantly. Groupon has had accounting issues and has had to restate its financial statements a number of times since it first filed to go public last year. It never has seemed to regain investors trust.

But gaining Coleman as a believer, even if it’s only a small investment, could give Groupon a boost. And with the shares still falling, it’s likely that Coleman has added to his position. George Soros’ hedge fund also bought Groupon’s shares in the third quarter.

Coleman has been an investing wunderkind. His biggest claim to fame was a big and early bet on Facebook (FB). This year Fortune included Coleman on our list of top business people under 40.

Still, most of Coleman’s biggest wins have come in Internet stocks. And he seems to be willing to bet on tech turnarounds. Along with Groupon, Coleman’s fund invested nearly $400 million in Yahoo in the third quarter.