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 Citadel Advisors, founded and run by Kenneth Griffin. It's one of the biggest hedge fund companies around, with a reportable stock portfolio totaling $72.5 billion in value as of March 31, 2014.

Citadel Advisors' latest 13F report shows that it boosted its positions in American International Group (NYSE:AIG), JDS Uniphase Corp (NASDAQ:JDSU), and Synovus Financial Corp. (NYSE:SNV).

American International Group, or AIG, is an insurance giant that has struggled since the recent credit crisis, even getting booted from the Dow. It has been getting back on its feet, though. It recently sold its aircraft-leasing business, ILFC, for $7.6 billion, and it has been profiting by specializing more -- in cyber-security insurance, among other things. Its latest quarter featured solid results, and its stock yields 0.9%.

JDS Uniphase is a telecommunications equipment maker that saw its shares plunge earlier this month after it posted weak third-quarter earnings and lowered its near-term forecast. Bulls still see potential, though, expecting data-center and cloud-computing build-outs to drive demand and telecom giants to eventually step up their capital spending. And management says it's seeing "strong bookings." In the meantime, the company's return on invested capital, net margin, and net income have been rising in recent years. And its weak third quarter's revenue rose as well, albeit by just 3%.

Synovus Financial, a 125-year-old Georgia-based bank, recently reported a strong first quarter, with net income tripling over year-ago levels on improved credit quality. Credit costs dropped by a whopping 64%. (Less exciting were rising costs and lower-than-expected mortgage-banking income.) CEO Kessel D. Stelling noted, "During the remainder of 2014, we expect continued loan growth, further improvement in credit quality, and a continued push on expense reductions." He added, "We are making strategic investments to improve our customers' experience and more effectively reach potential customers." These include newer, better ATMs and a multimedia branding campaign. Synovus stock yields 1.2%.

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Longtime Fool specialist Selena Maranjian, whom you can follow on Twitter, has no position in any stocks mentioned. The Motley Fool recommends American International Group. The Motley Fool owns shares of American International Group and has the following options: long January 2016 $30 calls on American International Group. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.