David Einhorn , founder of the $10 billion hedge fund Greenlight Capital, saw his gains for the year through November reach 11%, slightly below the S&P 500's gain of 11.9% for the same period. The investor had an eventful year, giving a take-down presentation of a big short position in AthenaHealth in October, taking the reigns as half owner and chairman of new homebuilder Green Brick Partners, and joining the activist chorus with a stake in EMC Corp disclosed in November.