What it's like going to the world's biggest horse sale, where royals and millionaires dropped $360 million this year on horses they hope might be the next Kentucky Derby winner

Katie Warren/Business Insider

Keeneland's September yearling sale has been called the "Super Bowl" of horse sales.

• Keeneland is the world's largest thoroughbred auction house.
• At the auction house's September yearling sale this year, buyers including Sheikh Mohammed of Dubai and billionaire businessman Vinnie Viola dropped more than $360 million on 2,855 1-year-old horses (called "yearlings") in the hopes they'll be the next great racehorses.
• The most coveted yearlings are offspring of former Triple Crown and Kentucky Derby winners.
• I spent a day at Keeneland's September auction, and I was blown away by the amount of money spent on horses that have never even been ridden.
• I was also surprised that the atmosphere was so casual, with people wearing baseball caps, polo shirts, and jeans.
• The bidding was so subtle that I couldn't even tell when people were bidding, and there were special "bid spotters" whose entire job is to watch for bids and alert the auctioneer.
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Every September, wealthy horse-racing fans, buyers, and sellers converge on Kentucky's second-largest city, Lexington, known as "the horse capital of the world."

Lexington is surrounded by hundreds of horse farms and is home to the world's largest thoroughbred horse auction house, Keeneland, which also hosts races. At Keeneland's September yearling sale, buyers drop millions on 1-year-old horses that have never even been ridden. In 2019 in particular, buyers spent more than $360 million on 2,855 of these horses (also called "yearlings") at the September sale.

Read more: I toured one of Kentucky's most legendary horse farms, where horses live in immaculate barns, security teams sweep the grounds at night, and Secretariat is buried. Here's what it looks like.

"We talk about this being the horse capital of the world, and it really is the place that's acknowledged around the world," Bill Thomason, president and CEO of Keeneland, told me in an interview during the September sale.

More than half of all horses born in the US are born within 30 miles of Keeneland, and the top stallions in the country are all within this 30-mile radius, according to Thomason.

"It's a concentration of an industry that's in this town with people whose livelihoods depend on this crop that they're producing, which are the yearlings," he said.

I flew down to Kentucky to attend the beginning of Keeneland's September yearling sale. Here's what it was like.