Welcome Back, Einhorn! Is Hedge Fund Back in Yahoo Fray?

It’s hard not to like the brainy David Einhorn, who runs Greenlight Capital, the New York hedge fund that often dips into tech investing.

That has included stakes in Microsoft and — for a short time last year — in Yahoo. But Einhorn, after initially seeing promise in CEO Carol Bartz and the Silicon Valley Internet giant’s assets in Asia, dumped his shares last July.

At the time, he noted he was unhappy with the noisy public fight Yahoo had gotten into with China’s Alibaba Group over its Alipay unit.

“The Partnership bought Yahoo! (YHOO) earlier this year based on a sum of the parts analysis, which included putting substantial value on its Chinese assets. Shortly after the purchase, the value of the Chinese assets came into doubt as the CEO of the Chinese unit hived-off a valuable subsidiary into a corporation that he personally controls. From there, the finger pointing started in every direction. This wasn’t what we signed up for. We exited with a modest loss.”

Last March, Einhorn had bought less than .65 percent of Yahoo, or about 8.5 million shares, which he said was due to his feeling that the company was undervalued with regard to its Asian assets.

Now it appears he has jumped back in a bit, holding just over three million shares of Sunnyvale, Calif.-based Yahoo at the end of the fourth quarter.

It’s not clear if he is still in or not — or if he might unite with another fellow hedgie, Third Point’s Daniel Loeb, who finally began his much-anticipated proxy fight for control of Yahoo today.

More to come, for sure.