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.

George Soros is known to some folks these days for his politics and philanthropy, but his fame stems from his wealth, which is a result of his outstanding investing prowess. He founded Soros Fund Management back in 1973 and, under its umbrella, the Quantum funds racked up an amazing record, reportedly averaging close to 20%.

As The New York Times has explained:

His huge gains have come from macro bets, which aim to profit from global economic trends by trading currencies, commodities, bonds and other securities. Mr. Soros made his name, however, betting on currencies.

The company's reportable stock portfolio totaled $9.3 billion in value as of September 30, 2012.

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

New holdings include Turquoise Hill Resources (NYSE:TRQ), majority-owned by U.K.-based mining giant Rio Tinto (NYSE:RIO) and focusing primarily on mineral mining in central Asia and Australia. Its Oyu Tolgoi mine in Mongolia is set to become one of the world's largest copper producers. If you're wondering why you haven't heard of this $7 billion company, until recently it used to go by another name, Ivanhoe Mines.

Among holdings in which Soros Fund Management increased its stake was Freeport McMoRan Copper & Gold (NYSE:FCX). Freeport has been hurt by low copper prices, higher costs of production, and global economic slowdowns, such as in China. On the plus side, though, it's a low-cost producer of copper and molybdenum, positioned to benefit quickly from upturns in metals pricing. Freeport has a balance sheet that's unusually strong, and an attractive valuation. It has a lot to offer patient investors, including a 3.3% dividend yield.

Soros Fund Management reduced its stake in lots of companies, including Westport Innovations (NASDAQ:WPRT). Westport designs low-emissions engines that run on natural gas, among other things. Its future seems bright, thanks to a growing interest in alternative fuels and currently low prices for natural gas. Some think those prices may stay low, benefiting Westport. New government mandates for vehicle makers to boost their average fuel efficiency can also boost Westport. In the meantime, though, it remains unprofitable, with even revenue dipping in its last quarter.

Finally, Soros Fund Management unloaded several companies, such as Amarin (NASDAQ:AMRN) and PotashCorp (NYSE:POT). Amarin, a late-stage cardiovascular-focused biotech company, has bulls excited about its newly approved drug, Vascepa. There could be more good news if the drug is approved for other treatments. In the meantime, there has been a lot of speculation lately about it being acquired by a big pharmaceutical company, with names such as AstraZeneca (NASDAQ:AZN) and Teva Pharmaceutical (NYSE:TEVA) being bandied about.

Major potash producer Potash has a lot going for it, but low natural gas prices have helped its fertilizer rivals produce nitrogen-based fertilizers inexpensively. A rise in those prices will help Potash, as will a global economic recovery, as some big contracts have been delayed recently. Some aren't too patient, though, as the company recently received a Wall Street downgrade due to lower expected production in the near-term.

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

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.