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 David Einhorn, highly regarded value investor and founder of Greenlight Capital. Einhorn's investing success, as well as his advocacy of financial transparency and accountability, has attracted many fans. Although he isn't afraid to short stocks, he prefers going long, looking 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 more than $5 billion. Greenlight Capital has averaged close to a 20% annual return since its 1996 inception.

Greenlight Capital's latest 13F report shows that it sold off a quarter of its shares of Rite Aid Corporation (NYSE:RAD). Why might it do that? Well, let's see.

Turning itself around
Rite Aid is in the midst of an impressive turnaround. A glance at its historical stock price is telling. Over the past 20 years, the stock averaged annual losses of about 0.5%. It averaged just a 1.9% gain over the past decade. And yet it has nearly quadrupled in value over the past year.

The 2013 fiscal year was one of the company's best ever, as it returned to profitability despite a slight downtick in revenue. Successful maneuvers have included shuttering underperforming stores while remodeling and relocating others. Rite Aid has also been focusing more on wellness initiatives. Its pharmacies, for example, have been pushing vaccines (as have its peers), and many Rite Aid locations are now dubbed Wellness Centers.

The company has been starting and extending some savvy partnerships, such as with McKesson (which delivers most of its prescription drugs) and GNC Holdings (which houses some of its stores within Rite Aid stores). CVS Caremark Corporation (NYSE:CVS) threatens Rite Aid's GNC partnership, though, with its new Family Vitamin Centers. (However, Rite Aid could get a boost from CVS' decision to stop selling tobacco products.)

Rite Aid's third-quarter report was mixed, featuring estimate-topping earnings and revenue up 2%, though management tempered near-term expectations. Its fourth-quarter and full-year results will be reported on April 10, so stay tuned if you're interested.

On the other hand...
Meanwhile, not everything is rosy at Rite Aid. It has been growing more slowly than its key rivals, and they're better positioned, competitively, with larger bases and healthier balance sheets. They're formidable foes.

Bears would also remind us that Rite Aid still carries a lot of debt -- more than $5.8 billion recently. Its return to positive free cash flow can help pay down that debt, but cash flow levels are still low, relative to debt.

Also consider
Even if you're bullish on Rite Aid, you might consider its rivals for your portfolio, too. For one thing, they pay dividends, with CVS Caremark recently yielding 1.5% and Walgreen Co. (NASDAQ:WBA) yielding 1.9%. CVS' revenue and earnings have been growing by about 8% to 10% annually over the past five years, while dividends have averaged 29%. Walgreen's revenue and earnings have been averaging single-digit growth over the past five years, and its dividend has averaged about 23% growth. CVS' forward P/E was recently 14.7, below its five-year average of 15.5, while Walgreen's was 16.9, a bit above its 16.6 average. Rite Aid looks cheaper than both, with its forward P/E of 12.3, but the others offer more stability and certainty.

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.