Every quarter, fund managers have to disclose what they've bought and sold. Their latest moves can shine a bright light on smart stock picks.

Today let's look at highly regarded value investor David Einhorn and Greenlight Capital, which he founded. Einhorn's investing success, as well as his advocacy of financial transparency and accountability, has attracted many fans. Although he isn't afraid to short stocks, he prefers going long, and he looks for situations where he feels a stock is mispriced.

Greenlight's stock portfolio totaled $5.2 billion in value as of Dec. 31, 2011, with about 41 holdings. The top three holdings, making up more than a quarter of the overall portfolio's value, are Apple, Microsoft, and General Motors.

Interesting developments
So what does Greenlight Capital's latest quarterly 13F filing tell us? Here are a few interesting details.

Several companies were new to the portfolio, such as OmniVision (Nasdaq: OVTI) and Research In Motion (Nasdaq: RIMM). OmniVision makes camera chips and is facing competition from Sony, posting falling revenue and earnings in its fiscal second quarter. While some have fled the stock, others see it as a bargain and even speculate that it might be bought out.

Research In Motion has fewer advocates these days, as its BlackBerry smartphones are losing market share to iPhones and Android devices. There's a ray of hope, though, as its new CEO stresses the more secure closed BlackBerry system. There's also speculation that the company may shift to focusing more on its software than on lots of hardware.

Greenlight upped its stake in Marvell Technology (Nasdaq: MRVL) during the quarter. Bulls are excited about Marvell's role in developing Google TV, and the company has also been praised for its effective stock buyback program.

Among the stocks that Greenlight cut back on was defense company Huntington Ingalls Industries (NYSE: HII). Various countries have been placing orders for military equipment, and Huntington is where they go for nuclear-powered ships and submarines, as well as many non-nuclear offerings. But investors still have to be worried about major reductions in the U.S. defense budget.

Finally, Greenlight sold out of several holdings, including touchscreen specialist Synaptics (Nasdaq: SYNA). Many are bullish on the company, given the ubiquity of touchscreen devices and their rapid proliferation. In its last reported quarter, Synaptics beat Wall Street estimates, but its revenue and earnings were still lower than a year ago.

We should never blindly copy any investor's moves, no matter how talented the investor. But it can be useful to keep an eye on what smart folks are doing. 13F forms can be great places to find intriguing candidates for our portfolios.

Looking for promising investments? Check out our free special report, "The Stocks Only the Smartest Investors Are Buying," and learn which stocks are appealing to Warren Buffett and other great investors.