Conquistador Cielo's loss in the Travers Stakes Saturday marks the end of his racing career, and also epitomizes the most disturbing trend in the sport.

Trainer Woody Stephens said today that the colt would be retired to stud in the wake of his third-place finish behind Runaway Groom here. "The owner and the syndicate have left it to me," he said, "and I think the colt should go home. I believe it's the right thing."

Stephens said that Conquistador Cielo had been suffering from a minor problem in his left leg before the Travers, and this was the reason he had been wrapped in front-leg bandages before the race. The colt came out of the race with a slight strain in a ligament outside his left ankle.

The injury is not serious; it probably was not enough to account for C.C.'s mediocre performance and is certainly not enough to end his career. Stephens said, "There was a little heat in the area this morning, but I think it could be taken care of in a few days."

The trainer said, however, that those few days would throw off the schedule he had mapped out for Conquistador Cielo. He wanted to run in the Woodward Stakes at Belmont Park on Sept. 4, but he couldn't make that race now. The Woodward would have been a crucial prep for the second leg of New York's fall championship series, the Marlboro Cup.

But the real reason for the colt's imminent retirement has little to do with his physical condition or his training schedule. It has to do with the changing economic structure of the sport.

Twenty-seven investors bought shares in Conquistador Cielo at $900,000 apiece, and they want to see their investment protected. In every case of such high-priced syndications, thoroughbreds have been shielded from risks and from possible defeats that could tarnish their reputation before they go to stud. In Europe, this trend has become so extreme that horses may race only half a dozen times in their careers. Storm Bird, the champion 2-year-old of 1980 in Europe, went to stud with a $30 million syndication and never even raced at 3.

Conquistador Cielo's one bad performance in the Travers can be rationalized away. Stephens attributed it principally to the race track, to the fact that his colt was pinned on the rail where the footing was disadvantageously deep. Some syndicate members will doubtless try to claim that the colt was hurt during the running of the race. But if Conquistador Cielo came back in the fall and gave another poor performance, his mystique would be gone. He wouldn't be worth $36.4 million any more.

Asked if he wouldn't like to have a chance to atone for the loss in the Travers, Stephens said, "What else could you prove? He's won seven races back to back. He won the Metropolitan Handicap and the Belmont. He did it all."

In fact, Conquistador Cielo didn't do it all. He will retire with many questions about his capabilities still unanswered.

In particular, he never proved that he was a true classic horse, one able to withstand pressure and win at 1 1/4 miles and beyond. On Saturday he looked like a typical son of Mr. Prospector who runs out of gas after nine furlongs. He never carried high weight. He never ran on the grass. His whole claim to greatness is based on the period between May 31 and June 5, 1982.

On the former date he broke Belmont's one-mile track record in the Metropolitan; on the latter he ran away with the Belmont Stakes. But this list of achievements is embarrassingly flimsy compared with the credentials of horses like Secretariat, Seattle Slew and Affirmed, who filled years (instead of a few days) with their great feats. Rarely has a thoroughbred earned such a reputation for so few accomplishments as Conquistador Cielo.