The Factor, who when right was one of the fastest horses in training, has been retired from racing and will stand stud at Lane’s End Farm in Lexington, Ky., it was announced Saturday. George Bolton, who co-owned The Factor with David Shimmon’s Fog City Stable, said The Factor had an injury to his left front ankle that would have required 60 days’ rest. Since he was going to miss races like the Santa Anita Sprint Championship and the Breeders’ Cup Sprint, the decision was made to retire him. “We’re retiring him completely sound, happily,” Bolton said Saturday at Parx where he was to run My Miss Aurelia in the $1 million Cotillion. The Factor, a son of War Front trained by Bob Baffert, sold for $250,000 as a 2-year-old at the Barretts auction in May 2010. He won 6 of 13 starts and earned $922,180. At 3, he went 4 for 7 with victories in the Grade 1 Pat O’Brien at Del Mar, the Grade 1 Malibu at Santa Anita, the Grade 2 San Vicente at Santa Anita and the Grade 2 Rebel at Oaklawn. This year at 4, The Factor won the Grade 2 San Carlos. He lost his last three starts, including a runner-up finish to defending sprint champion Amazombie in the Grade 1 Bing Crosby at Del Mar on July 29. Bolton, who will retain his share of the ownership of The Factor at stud, said The Factor would stand for $15,000. “We’re focusing on getting quality mares, hopefully for a 5- to 10-year period,” Bolton said. The Factor will ship from Southern California to Lane’s End on Wednesday, Bolton said. “The Factor showed brilliant speed and exceptional scope and quality in his three seasons on the racetrack, and Lane’s End is very pleased to stand this stunning horse whose pedigree will be of great interest to breeders,” said Will Farish, the owner of Lane’s End.