(Adds details on performance, background)
BOSTON, Aug 4 (Reuters) - Billionaire investor William Ackman's Pershing Square Holdings has risen 27.2 percent this year, according to an investor in the fund, after extending its gains modestly last month when many hedge fund managers suffered losses.
The Pershing Square Holdings fund inched up 0.6 percent in July. Performance at Ackman's $15 billion firm has long been watched closely, but never more so than now as he fights to seal a deal between drug companies Allergan Inc and Valeant Pharmaceuticals International Ltd. He also periodically presents new information to underscore his argument that nutrition and diet company Herbalife Ltd is running a pyramid scheme, something the company denies.
Performance numbers from other fund managers, including Daniel Loeb's Third Point, which fell 1.2 percent last month but remains up 4.7 percent year to date, show that July was a tough month for many hedge funds. The broader stock market sold off late in the month amid growing fears about U.S. interest rates and geopolitical concerns.
This year's returns rank Ackman among the industry's best performers and underscore just how much his portfolio has recovered from a year ago, when his short bet against Herbalife and a failed long position on retailer J.C. Penney took a bite out of returns. He exited the Penney bet in August 2013. Meanwhile, holdings such as Air Products & Chemicals Inc and Canadian Pacific Railway Ltd fared well last month.
The last few weeks have been eventful for the activist investor. He publicly ended a long-running feud with rival Carl Icahn with a hug, and a week later choked back tears during a fizzled presentation on Herbalife, when he called the company a criminal enterprise and compared it to drug dealers, failed energy company Enron and the Nazis.
On Friday, Botox maker Allergan accused Ackman, its biggest investor, of breaking insider trading laws while working with rival Valeant Pharmaceuticals. (Reporting by Svea Herbst-Bayliss; Editing by Chris Reese and Andre Grenon)