Figures for the First Four Days
According to ingame.com, during the first four days of the tournament, from 19 to 22 March, the total trading volume on Kalshi reached $2.34 billion. Commission revenue for this period amounted to $25.5 million. This is more than the platform earned in the first five months of 2025.
19 March, the first day of the tournament, became the second-highest trading day in Kalshi’s history after the Super Bowl. The single-day trading volume was $645.7 million, with commission income of $6.6 million.
Sport accounted for 90% of turnover across all four days. College basketball bets, excluding parlays, made up more than half of the turnover in the first round and around 40% in the second. Basketball alone brought the platform $13.2 million in commission over four days.
The week leading up to 23 March was a record-breaking one in terms of turnover in Kalshi’s history: $3.4 billion in total.
Individual Markets
The most heavily traded market in March was the contract for the overall tournament winner, which attracted $113.1 million in turnover.
The Duke vs Siena match recorded the highest turnover among individual games, at $42.4 million. This was largely due to the fact that New York prohibits licensed bookmakers from accepting bets on local university teams. Residents of the state had no other legal options for betting on a match involving Siena.
Iowa vs Florida took second place in terms of turnover among individual games with $24.7 million.
Kalshi’s Market Position
According to ingame.com, Kalshi is on track for a record year. In the first few months of 2026, the platform has already generated $340 million in commission revenue. By the end of the year, this figure could exceed $1 billion, placing Kalshi ahead of BetMGM and Fanatics in terms of volume in the US sports betting market.
By way of comparison: Polymarket US, which currently operates on an invitation-only basis, also recorded growth during the tournament. The volume of the global Polymarket exchange over four days amounted to $1.45 billion, of which $800 million was accounted for by sports contracts. However, the platform does not yet charge commissions on most markets and did not generate any revenue during this period.
Pressure from the NCAA
Against a backdrop of record-breaking volumes, the National Collegiate Athletic Association (NCAA) has spoken out against the involvement of prediction market platforms in betting on college sports. NCAA President Charlie Baker has written to the CFTC demanding a temporary halt to trading in event contracts linked to college competitions. The organisation cited threats to the integrity of competitions and the safety of athletes.
At the time of publication, the CFTC had not responded to this request. Kalshi continues to operate as normal.
The growth in trading volumes on Kalshi during a single tournament demonstrates how quickly sports contracts have evolved from a niche product into the platform’s main driver. A year ago, sports accounted for only a small share of trading. Now it accounts for 90% of trading volume on days of major events. This trend is intensifying pressure from regulators and traditional bookmakers, who see prediction markets as a direct competitor operating under different rules.
