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 investment advisory firm Douglass Winthrop Advisors. It's of interest because it employs a Foolish (in a good way) "low-turnover, buy and hold strategy."

The company's reportable stock portfolio totaled $1 billion in value as of March 31, 2014.

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

New holdings of interest include Houston-based oil and natural-gas company Linn Energy (OTC:LINEQ), which specializes in buying mature, productive energy assets and offers a hefty dividend yield of 10%. Linn Energy has been going through a bit of a rough patch lately due to its difficult acquisition of Berry Petroleum, for which some think it overpaid, and the company posted disappointing financial results in its last quarter. Still, bulls think there's much to like about the company -- besides its enormous and seemingly sustainable yield. Interested investors should learn more about the company's structure and its relationship with its affiliate, Linn Co.

Among holdings in which Douglass Winthrop Advisors increased its stake was Intel (NASDAQ:INTC). Intel offers a solid 3.3% dividend yield. It recently got the boot from Samsung tablets, lost some 64-bit ground to competitors, and has been late getting into Android devices. But all is not lost. The company recently reported its first-quarter results, with earnings down but still topping expectations and management pointing to 5 million tablet processors shipped. Cloud hardware sales have also been strong, and the company's cash flow remains prodigious, topping $10 billion annually. Bulls have high hopes for Intel's Broxton chip that serves both tablets and phones, as well as its enterprise server platform. Doubters want to see it performing more strongly in the mobile realm, where it has struggled.

Douglass Winthrop Advisors reduced its stake in lots of companies, including Celgene (NASDAQ:CELG), a biotech company. It's on a roll, thanks in part to its anemia drug Revlimid and pancreatic cancer drug Abraxane. Many are hopeful about its recently approved arthritis drug, Otezla, too. Celgene is investing heavily in other companies with promising early-stage drugs -- a move that can pay off handsomely in many years, not months. As my colleague Stephen Simpson has noted, Celgene has "a deep early stage pipeline of oncology drugs" and "meaningful label expansion opportunities for approved drugs." It appears to be undervalued, too, with its forward P/E ratio near 15. Celgene reports its latest results tomorrow, with investors watching to see how well Revlimid and Abraxane are selling and hoping to get an initial impression of Otezla sales, too.

Finally, Douglass Winthrop's closed positions of interest included Seadrill (NYSE:SDRL), a deepwater drilling specialist that has been dominating its realm and gaining market share in floating rigs and "jackup"  (i.e., self-elevating) rigs. A slowdown in offshore drilling is a concern, but the fact that recent contracts have featured much higher rates bodes well for the company, which has a large and young fleet of ultradeepwater rigs. Seadrill is well positioned for the long run, with a solid order backlog and an appealing valuation -- though it also carries a lot of debt.

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. 13F forms can be great places to find intriguing candidates for our portfolios.