The latest 13F season has arrived, 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 $76.8 billion in value as of Dec. 31, 2013. According to the folks at, Griffin and his team use "a combination of advanced computer code, complicated financial algorithms and secrecy. Griffin was using quantitative, technology-based methods before many other firms had cell phones."

Citadel Advisors' latest 13F report shows that it reduced its positions in Micron Technology, (NASDAQ:MU), LSI Corporation (NASDAQ: LSI), and Regions Financial Corporation (NYSE:RF).

Micron Technology recently reported a strong first quarter, with revenue surging 120% and earnings popping 165% over year-ago levels. With demand growing for solid state drives (SSDs), bulls like the company's investments in NAND memory technology and see demand for 3-D NAND technology driving growth at Micron and elsewhere. Micron stopped paying a dividend in the 1990s, but with its current strength and growing profit margins, some would like to see the payout reinstated. Meanwhile, some wonder whether the company might be acquired by a bigger technology company such as Intel or Apple. Its forward price-to-earnings ratio near 11 makes it even more attractive.

The big news for semiconductor company LSI is that Singapore-based Avago Technologies (NASDAQ:AVGO) is buying it for close to $6.6 billion. Management sees the deal immediately boosting Avago's bottom line and its cloud-computing business. Not everyone is thrilled with the deal, as a Florida pension fund has filed a lawsuit against LSI, alleging that the deal was structured unfairly. LSI specializes in flash storage, data centers, and mobile networks. Its last reported quarter featured revenue and earnings topping analyst estimates.

Southeast-focused regional bank Regions Financial performed well in 2013, improving its debt and capital structure and lowering its funding costs. Its net interest margin has increased steadily in recent quarters, too. Regions Financial's fourth quarter was a bit mixed, with earnings down from year-ago levels but full-year earnings up over the previous year and loans rising as well. (Business and auto loans were particularly strong.) Bulls like the bank's mobile ambitions and its innovations such as its Regions savings secured loan, a new fixed-rate installment loan responding to demand for (dangerous) payday loans. There's a lot to like about the company, but while net income has been growing in recent years, revenue has not. Regions Financial tripled its dividend in 2013 and recently yielded 1.1%.

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.