A yearling sale is a spectacle where most of the action is invisible. Only an onlooker with a trained eye can see a prospective buyer making a bid. A man might signify a $1 million bid with a waggle of the finger or an imperceptible nod of the head.

And much of the bidding may be illusory, anyway. A naive soul might watch a seemingly spirited auction, only to learn that the result was no sale, or that the whole deal had been prearranged. Behind-the-scenes intrigue and machinations are an integral part of the business.

Yet when the Saratoga Yearling Sales began on Tuesday night, spectators crowded the pavilion and pressed against its glass walls to catch a glimpse of the action, because an ordinary citizen rarely gets such a chance to see so much money changing hands so quickly. If we can be mesmerized by game shows with thousands of dollars at stake, how much more riveting is a game where millions can be spent in a minute, on a gamble of frightening proportions?

Although the Keeneland Yearling Sale is more expensive, it's strictly business. Saratoga is filled with glamor. The men are natty; their wives are bedecked with jewels. John Finney, president of the Fasig-Tipton Co. that runs the sales, says the buyers are all keenly aware of the presence of their peer group, and so the whole auction becomes a very stylized ritual.

When each horse is led into the ring, the announcer delivers a brief spiel about his virtues and the auctioneer begins his rapid-fire chant: "Who'll give me a hundred thousand to start? Well, fifty then! Fifty! Fifty! Now sixty!"

It is an unwritten rule that potential buyers signal the auctioneers or the tuxedoed bid-spotters as subtly as possible; nobody waves and (God forbid!) nobody yells. The representatives of British multimillionaire Robert Sangster and the Arab sheiks frequently will move behind pillars in the far reaches of the balcony to make their bids as discreetly as possible. Everybody else tries to emulate the big boys' discretion.

If the bidding lags, as it frequently will, the announcer will goad the reluctant buyers as unsubtly as a department store clerk eager to close a sale.

When the bidding for Tuesday night's top horse, a son of Seattle Slew out of the dam of Alydar, stalled at $1.6 million, Finney felt obliged to interrupt and lecture the bidders. "Excuse me," he said, "but this horse ought to be worth as much as any yearling here this year." At $2 million, Finney stepped in again: "I've got to say that this has to be a major disappointment at this money."

But the horse was sold for $2 million, and a sales slip was delivered to the buyers. This is a crucial moment in sales-ring etiquette. Buyers are supposed to look as blase' as possible, as if they're signing a charge slip for a sweater at Bloomingdale's.

Some of the Arab groups carry this demeanor to an extreme. When one sheik bought a $1 million daughter of Secreto, the whole group looked as if it was sitting in a dentist's office awaiting root canals.

The sales slip for a $2 million Seattle Slew yearling went to a man who looked as if he might have stepped off a tour bus, but Robert Marcus of West Palm Beach, Fla., is no stranger to the breeding game. As he coolly signed the slip, his wife Betty caressed his cheek and gave him a discreet kiss. This was very touching, but after the sale some cynics observed that the Marcuses had brought four horses from the same seller, Calumet Farm, and none from anyone else. The cynics wondered: Was this whole show prearranged? It wouldn't be a yearling sale without a few such rumors.

Underneath the cool, unemotional veneer of the sales, there is plenty of tension, because this is one of the riskiest businesses in the world and, in a market that has been plummeting, one that has cost plenty of people plenty of money. Many of the buyers are so wealthy that they don't have to worry about anything, but for many of the sellers this one night is a life-or-death proposition. The vagaries of the market can make or break them.

One youngster here learned about the harsh realities of the business late Tuesday night. Sixteen-year-old Brad Corbett had put up $1,000 when his father had bought a mangy-looking Spectacular Bid colt for $39,000 at a sale in the winter. The yearling had developed nicely, and before the sale one would-be buyer reportedly offered to buy him privately for $175,000.

Brad's father Brian Corbett said no. Father and son figured that if the colt could command such a private offer, he might bring as much as $250,000 in the ring. Their colt was selling late and, as the evening progressed, Brad's excitement was palpable: What a fabulous game!

But when the Spectacular Bid colt came into the auction ring, many buyers had straggled out of the pavilion to the next-door bar, and there was only one buyer seriously interested in the colt. Trainer Wayne Lukas -- who could, and possibly would, have spent much more -- got him for a bargain $100,000.

At 16, Brad Corbett learned a lesson that many others have learned at a far greater price. Beneath the cool, glamorous veneer, the yearling sales are a very tough business.