Einstein, a five-time Grade 1 winner, will enter stud with a $7,500 fee, Adena Springs announced Wednesday. An 8-year-old Spend a Buck horse, Einstein was to arrive at Adena Springs in Paris, Ky., at noon Thursday. Trained by Helen Pitts, Einstein earned Grade 1 triumphs in the 2009 Santa Anita Handicap on Pro-Ride, the 2008 Gulfstream Park Turf Stakes, the 2006 Gulfstream Park Breeders' Cup Stakes on turf, and back-to-back editions of Churchill's Woodford Reserve Turf Classic Stakes in 2008 and 2009. In his final start, Einstein finished third in the Grade 2 Clark Handicap in November. Adena's owner, Frank Stronach, who had purchased Einstein privately from Midnight Cry Stable last September, retired him when he suffered a soft-tissue injury while training for another tilt at the Feb. 6 Gulfstream Park Turf.