Cooperman bullish despite loss

Billionaire investor Leon Cooperman is still bullish on stocks despite a rare losing streak.

"We believe that the in-place U.S. equity bull market should last for quite a while longer, deliver moderate (high-single-digit) total returns rather than the strong double-digit returns of the past three years, be more volatile than in previous years and have greater breadth," the founder of hedge fund firm Omega Advisors wrote in a recent letter to investors obtained by ValueWalk.

Cooperman, who usually has a relatively positive bent on the markets, also wrote that he wasn't overly concerned about the looming increase in interest rates.

"The upcoming rate hike ... has been well telegraphed by the Fed and debated ad nauseam by investors," he explained. "We therefore expect it to have minimal, if any, impact on financial markets. One could even argue that it will be met with a degree of relief, as investors bear witness to its irrelevance."

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Those benign views come as Cooperman's investments have performed poorly.

His Omega Overseas Partners fund fell 3.57 percent in January, adding to a 2.13 percent loss over 2014, according to a report by HSBC's alternative investment group

The top losers last year, according to the letter, were Sprint (down 212 basis points, or 2.12 percent), Monitise (-205) and energy stocks like SandRidge Energy (-186), Atlas Energy (-86), QEP Resources (-67) and Atlas Resource Partners (-56).

"Our 2014 performance was embarrassing and we failed to deliver acceptable returns," Cooperman wrote in the same letter.

Cooperman's long-term track record is strong despite the loss. The main fund has generated compounded annual returns of 14 percent, net of fees, since 1991, according to someone familiar with the matter who added that 2014 was the first year in which Omega took losses even though the S&P 500, which rose 11 percent, was up.

Reached on the telephone, Cooperman declined to comment on whether or how he was repositioning his portfolio at the moment.

Cooperman told CNBC.com in late December that he'd be back.

"We are having a mediocre year, but our philosophy is if you made money for the clients, you get paid. If you lose money, you don't. Very simple but fair approach," Cooperman said. "Having done this for 46 years, I can tell you it's a marathon and not a sprint. Or as the Brooklyn Dodgers used to say, 'Wait 'till next year!'"

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CNBC's Kate Kelly contributed reporting.