The NFL’s Supreme Court brief said $1.8 billion of $3.3 billion in prediction-market trading on the 2026 season’s opening Sunday was tied to the league. That figure reflects notional trading volume, which measures potential contract payouts rather than the cash traders paid.
What the $1.8 billion measures
USA TODAY tested the claim using trading data and contract details from Kalshi and Polymarket US. Its analysis found that NFL-related contracts made up 59% of the two exchanges’ combined notional volume on Sept. 13, broadly consistent with the NFL’s estimate.
Kalshi and Polymarket together represented about 88% of trading across nine exchanges tracked by DeFi Rate during the 30 days ending Oct. 14. Notional volume counts the total potential payouts associated with contracts traded; it is not a tally of the money participants put down. The distinction matters when comparing prediction-market figures with cash wagered in conventional sports betting. The different measures are explored in this breakdown of prediction-market volume.
On a cash-paid basis, the NFL’s share was about half in Week 1, according to USA TODAY’s analysis. That share increased to 60% by Oct. 11, while the NFL-related share of notional volume rose to 69%.
The figure sits inside a regulatory fight
The NFL included the $1.8 billion figure in an Oct. 8 Supreme Court brief supporting New Jersey regulators in a dispute over whether sports contracts on prediction markets should fall under state gambling laws. Kalshi argues that its contracts are subject to the CFTC’s exclusive authority; some states treat them as sports betting subject to their gambling rules.
The size of the market also grew over the period USA TODAY examined. Combined notional volume on Kalshi and Polymarket US increased from $2.83 billion on Sept. 13 to $4.6 billion on Oct. 11, a rise of about 62%. The changing share of NFL-related trading therefore came alongside growth in the overall volume measured on those exchanges.
Combination trades and sportsbook competition
All-NFL combination trades were the fastest-growing category in USA TODAY’s analysis, rising from 30% of relevant volume on Sept. 13 to 45% on Oct. 11. A combination bundles multiple outcomes into one ticket, and every selection must be correct for the participant to receive a payout.
Prediction markets are also drawing more sports activity and competition from established sportsbook operators. Sports accounted for 78% of Kalshi’s trading volume and 82% of Polymarket’s in July 2026, according to a Pew Research Center analysis of data from The Block cited by USA TODAY. DraftKings launched DraftKings Predictions in December 2025 and DKeX in June 2026, while FanDuel Predicts also launched in December 2025. Those products place sportsbook companies in a market where sports contracts are central to the volume being reported.
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