Americans will legally wager $3.3 billion on the NCAA men's and women's basketball tournaments this year, the American Gaming Association said.
Betting on the tournament is expected to show an increase of 54% over the past three years, the trade group for casinos and sportsbooks said Friday, reflecting the growing number of states that have legalized such wagers.
The tally doesn't include casual wagers on office bracket pools and bets placed on prediction markets such as Kalshi Inc. and Polymarket.
Results can be hard to forecast. Last year the association predicted that $3.1 billion would bet, but after the tournament, the group estimated the actual amount bet was $2.7 billion, after wagering turned out lower than expected.
Sports wagers have grown rapidly on prediction markets since early 2025, when Kalshi and other exchanges began offering event contracts tied to games. Their sudden rise has sparked a legal fight between federally regulated exchanges and state regulators, who argue the exchanges are operating unlicensed sportsbooks.
While traditional sportsbooks take the opposite side of customers' wagers, prediction markets allow customers to trade yes-or-no contracts on the outcomes of games with each other.
Advertising by betting houses has declined as many of the companies throttle back early promotional efforts to increase profitability. Advertising peaked in 2021 at almost $900 million and will come in under $700 million this year, the group said.
Prediction market companies have increased their ad spending, according to the gaming association, which argues those businesses should be subject to state-by-state gambling regulations. They now account for 43% of the sports-betting ads seen by consumers.
Traders on Kalshi swapped $2.27 billion worth of contracts tied to men's college basketball in February, making it the leading sports category on the site.
Trading volume on prediction markets isn't directly comparable to betting volume on sportsbooks because prediction market traders can move in and out of the same position and take both sides of the same contract.
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