NEW YORK (Reuters) - William Ackman’s publicly traded hedge fund is outperforming the broader stock market this year, fueled by rising prices at Chipotle Mexican Grill and Automatic Data Processing Inc, the billionaire investor said on Thursday. “While a few months of strong performance is too short a period to judge our performance, we believe that (Pershing Square Holdings) is back on track,” Ackman wrote in his firm’s interim financial report. Pershing Square Holdings is up 12.7 percent this year through Aug. 7.