It was a tough July for hedge fund manager William Ackman, whose Pershing Square Capital Management lost 2.2 percent during the month, according to its latest performance update.
The hedge funds' total assets under management fell to $11.17 billion in July from $12 billion in June.
The fund got hit hard by its short position in nutritional supplements company Herbalife, which saw its share price rise more than 40 percent last month. Ackman's fund has invested $1 billion on a bearish bet that Herbalife will be unmasked by regulators as a pyramid scheme.
A long position in retailer J.C. Penney also hurt the fund, as the stock slid about 17 percent in July.
Pershing Square remains up 4 percent year to date. In contrast, the big-cap S&P 500 is up nearly 20 percent this year.
As of July 30 Pershing Square had incurred at least $300 million in losses on its Herbalife trade, according to a source familiar with the situation.
Last week, Ackman unveiled that he had made a $2.2 billion bet on Air Products & Chemicals. Pershing Square owns a 9.8 percent stake in the industrial gases giant, making it the company's biggest shareholder.
(Read more: Activist investor Ackman makes his biggest bet ever)
—CNBC with Reuters