The latest 13F season is here, when many money managers issue required reports on their holdings. It can be worthwhile to pay attention, as you might get an investment idea or two by seeing what some major investors have been buying and selling.

For example, consider George Soros, known to some folks these days for his politics and philanthropy. His fame initially stemmed from his wealth, though, which is a result of his 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% annual growth over four decades. 

Soros Fund Management's reportable stock portfolio totaled $10.1 billion in value as of March 31, 2014. Its latest 13F report shows that it established or added to positions in Atmel Corporation (NASDAQ: ATML), Brocade Communications Systems (BRCD), and Petroleo Brasileiro Petrobras SA (PBR 0.41%).

Atmel Corporation, which makes touchscreen controllers, has fans excited about its market share growth and growing number of new products. Its first-quarter results were impressive, with earnings more than doubling over year-ago levels and also surpassing analyst expectations. (Revenue, though, only grew by 2.4%.) Its forward P/E ratio near 12 is also appealing. Bulls -- and management -- also see a profitable role for the company in building out The Internet of Things.

Brocade Communications Systems has seen its stock surge more than 50% over the past year -- though it was up even more earlier in the year. The network data storage specialist still seems undervalued, with its forward-looking P/E ratio near 10, not to mention its growing margins. Still, revenue has not been growing very briskly, and there has long been speculation that the company might get bought out. Its most recent quarter featured revenue roughly flat over year-ago levels and adjusted earnings up 16%, with management noting a focus on serving data centers, which delivered the bulk of its revenue. It also introduced a dividend, which yields about 1.7% these days.

Petrobras, an oil giant majority-owned by the Brazilian government, also looks attractively priced, with its forward P/E ratio near seven. It sports promising offshore developments and is aggressively aiming to double production capacity by the end of the decade. But bears worry about its huge debt load, stalling production, and potentially costly corruption. Governmental meddling is another concern, such as when Brazil's government kept gas prices below Petrobras' costs.