LEXINGTON, Ky. -- Halo, sire of two Kentucky Derby winners, died Tuesday morning at Arthur Hancock III's Stone Farm in Paris, Ky. The stallion was 31 and had been pensioned since 1997.

A son of the celebrated Hail to Reason and 1974 broodmare of the year Cosmah (by Cosmic Bomb), Halo sired 62 stakes winners and seven champions. His progeny included 1989 Kentucky Derby winner and Horse of the Year Sunday Silence as well as 1983 Derby victor Sunny's Halo.

Other offspring were 2-year-old champion and noted sire Devil's Bag; North American champion mare and Canadian horse of the year Glorious Song; multiple Grade 1 winner Jolie's Halo; Grade 1 winner Goodbye Halo; and Grade 2 winner and popular sire Saint Ballado. Halo also twice led the general sire list.

Hancock said Halo's death came suddenly and may have been caused by a heart attack. "The night watchman came by and he was fine, and then he checked on him 30 minutes later and he had fallen over dead," he said. "He had no pain."

Breeder John R. Gaines sold Halo as a yearling at the 1970 Keeneland July sale, where he brought $100,000, more than triple the average for the auction that year. Campaigned initially by Mrs. Charles Englehard of Cragwood Stables, Halo won the Grade 2 Tidal Handicap, Lawrence Realization Stakes, and Voters Handicap. Windfields Farm bought Halo when he was 5, and he rewarded them with a Grade 1 win in the United Nations Handicap, his final race. He retired in 1974, after four seasons of racing, with a record of 31-9-8-5 and earnings of $259,553.

Windfields stood Halo in Maryland, where he got Canadian champion Glorious Song and multiple graded stakes winner Misty Gallore, among others, from his first crop. In 1984, breeders Tom Tatham and Dick Morris bought a combined 25 of the syndicate's 40 shares through their Tatham Corporation and moved the stallion to Stone Farm.

"Halo really probably saved Stone Farm in that he sired Sunday Silence after things got so bad and the market went to hell," Hancock said Tuesday.

"Whatever we had worth a dollar was worth 30 cents, and I had 4,600 acres with a lot of horses whose value had dropped to about a third. Times got tough. Then along came Sunday Silence."

Sunday Silence, whom Hancock raced in partnership with trainer Charlie Whittingham and Dr. Ernest Gaillard, was later sold privately to Japan's Shadai Stallion Station and is now a sire of legendary stature there.