August was a torrid month for hedge funds, and other prominent hedge fund managers have disclosed bets that have turned sour. Many funds were crowded in the same stocks that were hammered by the rapid sell-off last week.

Leon G. Cooperman, founder of the $9 billion Omega Advisors, told investors on Aug. 21 that he was down 11 percent for the month. Last week, William A. Ackman surprised investors by announcing that all the gains for his Pershing Square Capital Management hedge fund for the year had been wiped out by “significant volatility” in the global markets. Mr. Ackman’s multibillion-dollar hedge fund was down 7.3 percent for the quarter and 4.3 percent for the year as of Aug. 25.

The world’s largest hedge fund, Bridgewater Associates, led by Raymond Dalio, told investors that its Pure Alpha fund was down 4.77 percent as of Aug. 21. And the flagship fund of Third Point, led by Daniel S. Loeb, is up just 0.6 percent for the year, after losing 5.1 percent in August.

For Mr. Einhorn, this year has been one of bad timing and wrong calls. In July, Mr. Einhorn called his investment in SunEdison “our only significant winner,” adding that the stock had gone from $24 a share to $29.91 a share over the quarter. But in August, the stock took a sharp dive and is now trading at $10.40 a share.

Mr. Einhorn also bet heavily on the chip maker Micron Technology, increasing his stake in the company over the second quarter, according to the latest 13F filings.

Even so, he told investors in July that it was “our biggest loser” in the quarter. “It’s a cyclical business and, regrettably, we missed the turn of the cycle,” he told investors in a letter in July.

Along with gold, General Motors and Apple rank among his biggest long positions, both of which have had uneven returns in recent months. His fund has held a small position in Greek bank stocks and warrants. “Greece has been anything but sun-kissed,” Mr. Einhorn wrote in his July letter.