Beginning on Sunday, when he is almost certain to win a $100,000 race at Pimlico, Barry Weisbord figures to have a busy and profitable fall in Maryland. The wheeler-dealer from Kentucky owns Safely Kept, a 3-year-old filly who has won all six of her races this year and is one of the country's best sprinters of either sex. Because she is the daughter of a Maryland-based sire, she is eligible for the Maryland Million, and she will be the shortest-priced favorite of the day when she runs in the State of Maryland Distaff Handicap. Weisbord will be back in the state next month, for the first-ever Budweiser International Sale, an auction of stakes-class horses being held in the Laurel Sports Palace. The event is being run by the Matchmaker Group, of which Weisbord is president. The sale will be followed by the International Turf Festival, a two-day extravaganza featuring five major stakes races on the grass. Weisbord helped Laurel's late president Frank De Francis organize the event. And entries for the stakes are being solicited by -- who else? -- Weisbord's company. For a 38-year-old who broke into the business walking horses in the mornings at Aqueduct, Barry Weisbord has come a long way. He has become a force in many diverse aspects of the horse business because he has a genuine passion for the game, and because he conceived one brilliant idea and parlayed it to the hilt. Weisbord grew up in Lower Merion, Pa., where he and a high school classmate, Alan Goldberg -- now the trainer of Safely Kept -- developed their interest in horses. After Weisbord's junior year at the University of Pennsylvania, he and Goldberg tromped around the Aqueduct stable area, looking for a summer job. A trainer hired them as hot-walkers, and they were both hooked for life; Weisbord never went back to school. The two became partners when they bought a few claiming horses and raced them in Pennsylvania and New Jersey. In the late l970s, Weisbord's interest turned to the breeding end of the sport; some well-heeled investors put up capital that enabled him to get involved in the business' upper echelon. In his first notable transaction, he bought the mare Veruschka for $100,000 and later sold her for $850,000. Weisbord was entering the bloodstock business at a time when it was undergoing a major change. Once it had been very clubby; all of the big players knew each other, and most breeding deals were made privately. If Leslie Combs wanted to breed a mare to a stallion owned by Seth Hancock, Leslie would call Seth and they'd make a deal. But now many new players -- from Barry Weisbord to Arab sheiks -- were buying and selling thoroughbreds. "The game was getting so much bigger," Weisbord said, "that it was time to play it a little differently." So Weisbord conceived Matchmaker, a sales company that would serve as a marketplace for stallion shares and seasons. A breeder who owns the right to breed to the stallion Danzig could list him for $175,000 in the Matchmaker computer; another breeder could accept that price or make a lower offer via computer. Matchmaker collected an annual membership fee from everyone who used the service, plus a commission of up to 4 percent on each transaction. This was a revolutionary development in the breeding industry and, Weisbord said, "there was a lot of hostility to it." In the past, breeders could advertise phony prices and conceal the real stud fee for a stallion. Now the game was being played out in the open, and if a stallion's fee had dropped from $40,000 to $5,000, the world knew it. Some breeders still resent Matchmaker and resist having their stallion's shares traded publicly, but the concept has become so well-entrenched that Weisbord and Matchmaker are now important fixtures in the thoroughbred industry. From that beginning, Matchmaker branched into other aspects of the horse business. Weisbord saw that there aren't many opportunities for a buyer to acquire a ready-to-run stakes horse, and he thinks the forthcoming auction at Laurel -- a "boutique sale," he calls it -- will fill that void. Weisbord has also ventured into an area that others were fleeing: financing the purchase of horses. As bloodstock values have plummeted in recent years, many banks that made loans on horses were being hard-hit by losses. But Weisberg and his associates figured they had an edge because of their knowledge of the thoroughbred business. Whereas banks looked at the buyer's financial statement, Weisbord's firm would look at the quality of the horses being bought. "We'll lend on a good horse and a bad statement," he said. Weisbord found another outlet for his talents when he met De Francis, got involved in promoting the International and then sold De Francis on the idea of the Pimlico Special -- a rich stakes race for older horses, one week before the Preakness, which has turned into a spectacular success. "If there's one thing I thought I'd be really good at, it's designing races," Weisbord said. "Going to good races is what I love. And the idea of doing something like the Pimlico Special -- it's like inventing the Rose Bowl!" Yet even after all of his diverse successes, Weisbord hasn't strayed very far from his origins in the horse business. He and Goldberg are still allies, though Goldberg has continued to devote his full-time efforts to training. "He's very, very good -- much better than I would have ever been," Weisbord said, "and he's done a stupendous job managing Safely Kept." But while the two old pals started buying $10,000 claimers, they can now play in the big leagues. Weisbord buys horses from Europe and hopes to turn them into major stakes winners here. He spent $300,000 for Safely Kept when she was a 2-year-old, and she has developed into a prime contender for the $1 million Breeders' Cup Sprint -- the kind of success, in other words, that characterizes most of her owner's ventures.