By Svea Herbst-Bayliss and Richard Valdmanis
BOSTON (Reuters) - Hedge fund mogul William Ackman, one of last year's best performers, joined a string of high profile managers in reporting deep losses for August as global markets tumbled amid fears over slower growth in China.
Ackman's Pershing Square Capital Management, which makes concentrated bets on a small number of stocks, told clients on Wednesday that its Pershing Square LP fund fell 7.7 percent last month, leaving it flat on the year with a 0.06 percent gain.
The firm's Pershing Square Holdings portfolio dropped 9.2 percent, and is now down 0.1 percent for the year, erasing a 10 percent gain it had at the end of July, two sources familiar with the numbers said. Last year the fund gained 40 percent, beating the Standard & Poor's 13.7 percent gain.
Ackman warned investors in a letter last week that tumbling markets had wiped out gains. The decline moderated slightly when the market rebounded some late last week.
The shift of fortunes shows how much market volatility, sparked by sharp declines in Chinese stock prices, has
hurt the world's most prominent investors.
Although some investors, like managers, grumbled about August's rout, several said hedge funds were largely still beating the broader market. The Standard & Poor's 500 fell 6 percent in August while the average hedge fund lost 2.2 percent, data from Hedge Fund Research show.
Leon Cooperman's Omega Advisors closed the month with a 6 percent loss, while Dan Benton's Andor Capital, which invests heavily in technology stocks, fell 4.5 percent, investors said.
Viking Global Investors dropped 2.1 percent in August but is still up 7.4 percent for the year, a person who saw the number said.
On Monday, David Einhorn, who runs Greenlight Capital, and Daniel Loeb, who leads Third Point, said they each lost roughly 5 percent last month, while Barry Rosenstein's Jana Partners fell 4.3 percent. Greenlight is now down nearly 14 percent for the year, one of the industry's most high-profile losses.
Activist investors such as Ackman and Rosenstein are seen as being especially vulnerable to market downturns since many of their investments involve buying undervalued stocks and holding them while trying to persuade corporations to unlock value.
Clifton Robbins's Blue Harbour Group, which also tends to invest in activist situations, fell 2.56 percent last month and Scott Ferguson's Sachem Head Capital guided investors that its returns would be off roughly 2 percent, investors said.
There were also winners. Investors said Visium Asset Management's Balance Fund inched up 0.57 percent last month, gaining 11.2 percent for the year. The HG Vora Special Opportunities fund is up 8 percent for the year after rising 0.20 percent in August. Newcomer Clearfield Capital, which counts Ackman among its investors, was flat on the month and is flat on the year, people familiar with the funds' returns said.
(with additional reporting by Lawrence Delevingne in New York; Editing by Chris Reese, Andrew Hay and Ken Wills)