The latest 13F season is commencing, when many money managers issue mandatory 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 D. E. Shaw. Founded by David E. Shaw, it has a reportable stock portfolio totaling $73.3 billion in value as of Dec. 31, 2013. Shaw is known as a math wizard and a quantitative-investing pioneer. His firm is reportedly extremely selective when hiring, said to accept about one in 500 applicants -- CEO Jeff Bezos once made the cut.

D. E. Shaw's latest 13F report shows that it upped its holdings of Micron Technology (MU 1.70%), Rite Aid (RAD -58.33%), and Frontier Communications (FTR).

Micron Technology's first quarter featured revenue up 120% and earnings rising 165% from year-ago levels. The purchase of the Japanese company Elpida has been a game-changing move, turning Micron into the world's second-largest DRAM maker with twice the company's previous memory capacity, more pricing power, and more production facilities. With demand growing for solid state drives, bulls like the company's investments in NAND memory technology. Many would like to see its dividend resurrected, too. At an analyst conference earlier this month, management said it was focused on "operational excellence and deployment of advanced technology," as well as decreasing debt, among other matters.

Rite Aid has been executing an impressive turnaround. The drugstore chain has struck or extended 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 locations). Rite Aid has been growing more slowly than its key rivals, but it still seems cheaper than those retailers. Its third-quarter report was mixed, featuring estimate-topping earnings and revenue up 2%, but management tempering near-term expectations. Bears would also remind us that Rite Aid still carries a lot of debt.

Frontier Communications had a great 2013, rising 21%. The telecom company offers a big 8.6% dividend yield -- but it also carries considerable debt, which could threaten that payout. Not helping the debt situation is Frontier's recent decision to buy AT&T's wireline business and statewide fiber network in Connecticut for $2 billion in cash. Frontier Communications expects the deal to boost free cash flow in the near term, though, and it has been shifting its focus from landline operations toward higher-margin operations such as broadband and serving business customers. Its recently reported fourth quarter featured roughly flat revenue, which was better than the loss that had been expected, while its earnings also delivered a surprise bit of growth.