The late John Gaines is said to have joked once that the secret to success in the horse business is to buy what Arthur Hancock can't sell. It was more than 20 years ago that Hancock, a prominent breeder and owner in Kentucky, was unable to move a dark bay colt by Halo at two separate auctions. He ended up racing Sunday Silence in partnership, and in 1989 the horse reeled off wins in the Kentucky Derby, Preakness, and Breeders' Cup Classic.\nSaturday, another horse Hancock was unable to sell at auction, Sumo, will run in the Grade 2, $500,000 Indiana Derby at Hoosier Park. He does not have the kind of credentials Sunday Silence had built up leading into the fall of his 3-year-old season, but Sumo has shown promise. For his win in the $70,000 Pleasant Colony at Saratoga in his last start Aug. 26, he earned a career-best Beyer Speed Figure of 96. The number is the highest last-race Beyer in the Indiana Derby.\n"I think the jury is still out on him, but he did beat some nice horses in the Pleasant Colony, and he had a pretty good Beyer," Hancock said of Sumo. "He seems to be improving. He's kind of on the cusp right now. This is a big race for him."\nSumo, who is trained by Graham Motion and will be ridden by Calvin Borel, was one of 15 horses entered in the Indiana Derby. The 1 1/16-mile race will be limited to a field of 12. It is one of four stakes worth a cumulative $750,000 on the program, which is the richest for Thoroughbreds in Indiana.\nHancock, 66, operates the 2,000-acre Stone Farm in neighboring Kentucky. It was there that Sunday Silence, who was the Horse of the Year in 1989, was raised. So was Sumo. The two share more than that in common. Sunday Silence went through the auction ring without success as a yearling and again as a 2-year-old. Sumo, meanwhile, fell about $15,000 short of reaching his reserve at a yearling auction at Saratoga in 2007.\n"He didn't sell," Hancock said. "He was a little small, and of course, first foals can be that way. I wanted $200,000. I almost sold him and didn't, so we kept him."\nSumo is from the mare Dyna Da Wyna, a Grade 3 winner of $365,740. Hancock bought her in foal to Fusaichi Pegasus, the 2000 Kentucky Derby winner, for $500,000 at auction at Keeneland. Hancock bred Fusaichi Pegasus in partnership with Stonerside and later sold him as a yearling for $4 million. Dyna Da Wyna is by Doc's Leader.\n"I saw her going into the ring, and I thought she was a beautiful mare," Hancock said. "And, we bred and sold Fusaichi Pegasus."\nLike Hancock, the Maryland-based Motion sees Sumo as a developing horse right now. Back in December, he sent him out to win his maiden at a mile at Laurel. One start later, Sumo stepped up and won a $50,000 optional claiming allowance route at Tampa Bay Downs on Jan. 30, despite some drifting antics.\n"He ran very immaturely at Tampa when he won the allowance, but I think he's really grown up a lot," Motion said. "It was evident in his race at Saratoga."\nSumo stalked the pace, overtook the leaders, and went about his business for a five-length score in the Pleasant Colony. It was his first win since the Tampa allowance, with the spaces in between being filled by a runner-up finish to eventual Grade 1 Blue Grass winner General Quarters in the Grade 3 Sam F. Davis in February, and a ninth-place finish in the Grade 3 Tampa Bay Derby in March.\n"Mr. Hancock decided to give him some time after the Tampa Bay Derby, and it really helped him," Motion said.\nMotion is in his first full year of training for Hancock, who in addition to Sunday Silence was the co-owner of another Kentucky Derby winner, Gato Del Sol, in 1982.\n"He's a true horseman," Motion said. "He really understands from a trainer's perspective what you deal with on a day-to-day basis, and he's quick to do the right thing by his horses. It makes my job easier."\nHancock is the son of the late Bull Hancock, who was the master of Claiborne Farm in Paris, Ky., from 1947 until his death in 1972. During that period, Bull Hancock put together a stallion roster that included Nasrullah, Bold Ruler, Buckpasser, and Nijinsky II. The star-studded lineup would later include Secretariat.\nArthur Hancock oversaw a small parcel of land for his father, also in Paris, Ky., that he eventually developed into Stone Farm. In addition to Sunday Silence, the farm has raised such top-class 3-year-olds as Risen Star, Fusaichi Pegasus, and Menifee. Sumo will try to add his name to the honor roll come Saturday.