Regulatory filings made with the Securities and Exchange Commission detailing what Wall Street's savviest investors owned at the end of the fourth quarter paint a mixed picture. Some hedge funds dumped all of their holdings while others hedged their bets by getting rid of some but not all of their investments in companies involved in the high-risk but potentially high-reward business of finding and producing oil and gas.

For example, Leon Cooperman's Omega Advisors, long considered one of the industry's top stock pickers, liquidated its entire 3.7 million share investment in Denbury Resources Inc (>> Denbury Resources Inc.) during the three months, when its stock price dropped 44 percent, a filing with the Securities and Exchange Commission showed.

But at SandRidge Energy Inc (>> SandRidge Energy Inc.), where Omega ranked as the third-largest investor at the end of 2014, Cooperman cut only 29 percent of his position, selling 13 million shares to own 32 million.

Last year Omega Advisors fell 2.13 percent, according to a person familiar with his numbers. Hedge funds, on average, gained 3 percent, research firm Hedge Fund Research reported. Omega's performance got off to a rocky start in January 2015 with losses, but keeping some exposure to SandRidge was a good call as the stock has climbed nearly 30 percent since Jan. 1.

Meanwhile Cohen's Point72 Asset Management, which invests Cohen's roughly $10 billion personal fortune, slashed its investment in natural gas producer Range Resources Corp (>> Range Resources Corp.) by 65 percent during the fourth quarter as its stock price dropped 20 percent.

The stock is off roughly 2 percent this year and the company plans to cut its capital budget for the current year because of falling commodity prices.

Halcon Resources Corp (>> Halcon Resources Corp), whose share price fell 54 percent during the fourth quarter, also said it was cutting its capital budget for 2015 to conserve cash and avoid a fire sale to a rival.

Several prominent investors, including Rainier Investment Management and Regiment Capital, adjusted their portfolios late last year. Rainier liquidated its 2.5 million share-stake in Halcon, according to a filing. It also sold its interest in oil services company Halliburton Co. (>> Halliburton Company), which is buying rival Baker Hughes Inc (>> Baker Hughes Incorporated).

Regiment Capital meanwhile made only a small adjustment by selling 50,085 shares of Halcon, cutting its stake by 2 percent, the filing shows.

Cimarex Energy Co (>> Cimarex Energy Co), whose share price dropped 16 percent during the last quarter but has risen 6 percent this year, has attracted some buying interest.

During the fourth quarter, Diamond Hill Capital Management increased its investment in Cimarex by 16 percent to 3.1 million shares. But Senator Investment Group liquidated its investment, selling 1.9 million shares.

(Reporting by Svea Herbst-Bayliss; Editing by Steve Orlofsky)

By Svea Herbst-Bayliss