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 highly regarded value investor David Einhorn and Greenlight Capital, which he founded. Einhorn's investing success as well as his advocacy of financial transparency and accountability have attracted many fans. Although he isn't afraid to short stocks, he prefers going long, and looks for situations where he feels a stock is mispriced. He started Greenlight with less than $1 million, and it now boasts a stock portfolio worth $6.7 billion.

Greenlight Capital's latest 13F report shows that it sold General Motors Company (GM -1.85%), Marvell Technology Group Ltd. (MRVL 0.55%), and Rite Aid Corporation (RAD).

General Motors is facing a big headwind in costs related to many recalls and litigation. According to, "GM has now recalled more cars for safety problems this year than it sold all last year (9.7 million)." Despite that, though, its first-quarter results exceeded expectations -- though earnings took an 82% hit. The company has been doing many things right, such as applying more discipline to pricing and incentives. It has a lot riding on its Silverado truck, too, which has been redesigned. General Motors stock yields a generous 3.5% for investors with faith in new CEO Mary Barra.

Marvell Technology Group, a chip specialist, has been struggling, with revenue growing slowly over the past three years, while profit margins and free cash flow shrank. Bulls are hopeful about its prospects, though, due to the growing adoption of solid-state drives (SSDs) and global demand for data storage, not to mention the growing LTE market in China. They like its valuation, with a forward P/E ratio near 15, too. The company topped expectations in its fourth quarter and is set to report its latest quarterly results on the 22nd. Marvell stock yields 1.5%.

Rite Aid Corporation has been executing an "explosive" turnaround, and its shares are near a 52-week high. It has been closing some stores, while redecorating and relocating others. It's creating "wellness stores," too, and has also acquired a chain of retail health-care clinics. Rite Aid's last quarter was a great one, trouncing expectations as earnings soared nearly 43% over year-ago levels and also featuring management upping its projections. Generic drugs, which offer fatter profit margins, are likely to boost Rite Aid's bottom line, and analysts expect much faster growth from it than from its rivals. Still, don't forget that the company carries a lot of debt.