Every quarter, many money 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 have attracted many fans. Although he isn't afraid to short stocks, he prefers going long and looks for situations where he feels a stock is mispriced.

Greenlight's stock portfolio totaled $5.5 billion in value as of March 31, 2012, with about 41 holdings. The top three holdings, making up more than a quarter of the overall portfolio's value, are Apple, Seagate Technology, and General Motors.

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

New holdings include grocery store company Roundy's (Nasdaq: RNDY) and IT service provider Computer Sciences. Roundy's, with a strong presence in the Wisconsin and surrounding areas, traces its roots back to 1872, though it's newly trading as a public stock. Some worry about its debt load, but others like the growth potential of its stores. Recent growth has disappointed, though.

Among holdings in which Greenlight increased its stake were DST Systems and Marvell Technology (Nasdaq: MRVL). DST provides software services to industries such as financial services and communications and has seen its revenue growth stall and its earnings drop. Chip designer Marvell has been making some smart acquisitions, and my colleague Anders Bylund is bullish on Marvell because of big orders from China and pent-up demand following Thailand's industry-disrupting floods.

Greenlight reduced its stake in companies such as Research In Motion (Nasdaq: RIMM) and Xerox (NYSE: XRX). BlackBerry maker Research In Motion has seemed to be in death throes lately, but some see a few signs of hope, such as solid sales in emerging markets. Xerox may seem like a yesteryear stock to some, but it has others drooling at its cash pile and low valuation. The company has been focusing more on services lately and has been turning itself around.

Finally, Greenlight unloaded several companies, such as OmniVision Technologies (Nasdaq: OVTI). OmniVision is in the rapidly growing smartphone component business, but it also lost a contract with Apple recently, which doesn't bode well. This has led some investors to flee, but others have seen it as a relative bargain.

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. 13-F forms can be great places to find intriguing candidates for our portfolios.

If you're looking for ways to profit from the booming demand for tablets and smartphones and would like to consider candidates other than OmniVision, check out our special free report, "The Next Trillion Dollar Revolution" -- which names names.