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 GMT Capital, a private investment company that manages several hedge funds and other accounts. Its stock portfolio totaled $3.7 billion in value as of Dec. 31, 2011. You don't generally grow that large without doing some things right.

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

New holdings include Travelzoo (Nasdaq: TZOO), which is down roughly 75% from its 52-week high. Its revenue has been growing, but its earnings have not, and subscriber growth has slowed, as well. The company offers daily deals like many others these days, but many investors have lost their enthusiasm for that business model.

Among holdings in which GMT Capital increased its stake were Stillwater Mining (NYSE: SWC) and Manitowoc (NYSE: MTW). Stillwater shed a lot of value last year, partly due to volatility in platinum and palladium prices. To some investors, that makes its stock much more of a bargain -- especially if the high price of gold drives more jewelry purchasers toward platinum. Manitowoc, which specializes in cranes and food service equipment, has been growing well, introducing new products and expanding into emerging markets. It's poised to benefit from the global economic recovery, but it's also saddled with a lot of debt.

GMT Capital reduced its stake in a bunch of companies, including glass and fiber optic giant Corning (NYSE: GLW). Bulls love the success of its Gorilla Glass, which has found its way into many devices such as smartphones and tablets, but others worry about lackluster LCD TV sales. The company also sports a healthy balance sheet, offers a 2.1% dividend yield, and is investing heavily in innovation. (If the explosive growth of smartphones has you excited, you can make money off them through other stocks besides Corning. Check out our special free report, "3 Hidden Winners of the iPhone, iPad, and Android Revolution," to learn about some compelling candidates for your portfolio.)

Finally, GMT Capital unloaded several companies, such as American Superconductor (Nasdaq: AMSC), which suffered greatly last year when it lost a lot of business from a customer on which it was very dependent. It's also burning through a lot of cash.

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

Longtime Fool contributor Selena Maranjian, whom you can follow on Twitter, owns shares of Corning, but she holds no other position in any company mentioned. Click here to see her holdings and a short bio. The Motley Fool owns shares of Corning. Motley Fool newsletter services have recommended buying shares of Corning and Travelzoo. The Motley Fool has a disclosure policy. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. Try any of our Foolish newsletter services free for 30 days.