David Einhorn's Greenlight Capital deftly maneuvered through July's volatility and unpredictability to post a 1 percent gain for the month. As a result the hedge fund manager, who is on the verge of completing his deal to buy a stake in the New York Mets, trimmed his 2011 loss to 4.2 percent. Einhorn solidly beat the S&P 500, which lost 2.15 percent in July.