Every quarter, many money managers have to disclose what they've bought and sold, via "13F" filings. Their latest moves can shine a bright light on smart stock picks.

Today, let's look at 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 mis-priced.

The company's reportable stock portfolio totaled $5.3 billion in value as of June 30, 2013.

Interesting developments
So what does Greenlight's latest quarterly 13F filing tell us? Here are a few interesting details:

The biggest new holdings are ING U.S. (VOYA -2.37%) and Liberty Global. ING U.S. is a new IPO, expected to be rebranded as Voya Financial. It's the U.S.-based retirement, investment and insurance operations of financial services giant ING Groep, which is based in the Netherlands. Its second quarter featured operating earnings up 36% over year-ago levels, but a bottom line in the red. Management cited a rise in operating return on equity, and noted, "...we continued to reposition our Individual Life segment with a focus on less capital-intensive products, while also investing in our Employee Benefits product set." The company was one of a bunch of life insurers involved in a settlement over unpaid life insurance benefits.

Other new holdings of interest include beleaguered drugstore chain Rite Aid (RAD -51.21%), which has actually seen its stock nearly triple over the past year. Along with its rivals, it stands to benefit from Obamacare, which should deliver more insured Americans demanding more medications. But Rite Aid is also carrying much more debt than its rivals, and has been addressing that, in part, by closing some stores. Still, it's posting growth and net gains instead of losses lately, so there is reason to be hopeful.

Among holdings in which Greenlight Capital increased its stake was the Market Vectors Gold Miners ETF (GDX 3.65%). It has underperformed the world market over the past three and five years, but is still of interest to those bullish on bullion. Its top three holdings, with more than a third of the fund's assets, were Goldcorp, Barrick Gold, and Newmont Mining, as of the end of July. The ETF levies an expense fee of 0.52%, and it recently yielded about 1.7%.

Greenlight Capital reduced its stake in lots of companies, including Marvell Technology (MRVL 4.06%) and Computer Sciences Corp. (CSC). Chipmaker Marvel specializes in storage, and recently posted solid second-quarter earnings. It topped analyst estimates, but still saw its stock sink, in part due to concerns over its networking business. Bulls like its diversification, new-product development, and proprietary technologies, and see it as undervalued, with its forward P/E near 16.5. It yields 2%, and has been buying back lots of shares, reducing its diluted share count from 677 million in 2011, to 541 million recently.

Information technology outsourcing and service provider CSC posted solid first-quarter results, featuring estimate-trouncing net income, up 279% over year-ago levels. (Revenue was down 10%, though.) The company has been shifting its focus from infrastructure sales, to more profitable software and services, and recently bought big-data company Infochimps. The company is under new management, and has been turning itself around, with some seeing it as attractive now.

Finally, Greenlight's biggest closed positions included Virgin Media and Seagate Technology. Other closed positions of interest include Western Digital. Western Digital and Seagate Technology control about 85% of the hard-disk drive market. Despite worries about a shrinking PC market, bulls see a massive and growing need for storage, and view hard-disk drives as inexpensive solutions for that. While Western Digital has partnered with others in order to compete in solid-state drives, Seagate has been building its own SSD business.

We should never blindly copy any investor's moves, no matter how talented the investor. But it can be useful to keep an eye on what smart folks are doing. Therefore, 13-F forms can be great places to find intriguing candidates for our portfolios.