Every quarter, many money managers have to disclose what they've bought and sold, via "13F" filings. Their latest moves can shine a bright light on smart stock picks.

Today, let's look at PartnerRe Asset Management, a subsidiary of the $5 billion PartnerRe reinsurance company. It invests in stocks, bonds, and mutual funds for its clients, and its reportable stock portfolio totaled $1.2 billion in value as of Sept. 30, 2013.

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

The biggest new holdings are Twenty-First Century Fox and Delta Air Lines. Other new holdings of interest include Vertex Pharmaceuticals (NASDAQ:VRTX), whose cystic fibrosis drug, Kalydeco, has much potential. (It's looking to expand approvals for the drug, too.) Vertex's hepatitis C drug, Incivek, once the fastest-growing, is challenged by compelling competition, though. Vertex's history offers valuable lessons to investors, such as the importance of patience and how a company's prospects can change quickly.

Holdings in which PartnerRe increased its stake were Freeport McMoRan Copper & Gold (NYSE:FCX) and Micron Technology (NASDAQ:MU). Freeport, the world's largest publicly traded copper producer, has been challenged by falling copper and gold prices. Bulls see copper rebounding, however, and analysts at Goldman Sachs have named it as a top pick in its industry. Freeport's second quarter was encouraging, featuring estimate-topping earnings (and revenue a bit below expectations), along with effective cost-cutting. Its recent purchases of oil and gas exploration and drilling companies diversify its operations. Its stock yields 3.7%.

Memory giant Micron has been successfully adapting to a changing market. Bulls are excited about its acquisition of Japanese manufacturer Elpida, which has boosted its capacity, its pricing power, and its relationship with AppleBears haven't liked recent net losses and shrinking margins, and want to see solid results from its solid-state drive-related operations. It faces able competition, but with its forward P/E is near 10, Micron seems appealingly priced. (It won a legal victory against a key rival recently.) A recent short-term boon for Micron is a fire at a competitor's plant, which sent some chip prices to a two-year high.

PartnerRe's biggest closed positions included News Corp. and Sprint Nextel. Other closed positions of interest include Advanced Micro Devices (NASDAQ:AMD) and Windstream (OTC:WINMQ). Advanced Micro Devices, or AMD, has been in penny-stock territory all year. Bears see it threatened by a weak PC market and don't like its heavy free-cash-flow losses in recent years. Still, bulls are hopeful about its recent cost-cutting and its growing focus on gaming technology, where it's taking on NVIDIA in gaming chips. A turnaround may be under way, but investors should tread carefully.

Windstream (NYSE: WIN) has seen its stock slide in recent years, as its future presents considerable uncertainty. Windstream has been shifting its focus away from rural telecom service and toward broadband service and business customers, but it's also been losing customers (though its enterprise customer count recently grew by 6%). It sports a dividend that has been yielding more than 12%, though, and management has maintained the dividend --  for now. There's still reason to be hopeful, as it sports positive free cash flow and solid growth potential, but the stock remains heavily shorted.

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.