As the NFL surges through its regular season, so too do prediction markets.
That’s the picture the league painted in an Oct. 8 Supreme Court brief that claimed $1.8 billion out of $3.3 billion in prediction market trading on the first Sunday of the 2026 season was NFL-related. If true, that figure means that about 55% of prediction market volume for apps like Kalshi and Polymarket was related to the league on Sept. 13.
However, the brief doesn’t cite where those figures came from or how they were structured, and the NFL declined to comment on its brief.
USA TODAY attempted to replicate the NFL’s findings by analyzing trading data published by Kalshi and Polymarket US, along with contract details from each exchange’s API. We found the NFL’s figures to be roughly accurate.
USA TODAY specifically calculated that 59% of notional volume on the NFL’s opening Sunday across both exchanges — which together accounted for about 88% of trading across nine exchanges tracked by prediction-market data site DeFi Rate over 30 days ending Oct. 14 — was related to the NFL. That share grew each following week and was up to 69% by Oct. 11.
Notional volume measures the total potential payouts of contracts traded, rather than the actual amount of money traders paid.
Representatives for Kalshi and Polymarket confirmed USA TODAY’s findings to be directionally accurate.
The difference between USA TODAY's findings and the NFL's figures could reflect which exchanges were included or how NFL-related contracts were counted.
Polymarket told USA TODAY that it prefers tracking taker volume instead of notional. In an interview with CNBC, the company’s head of revenue and analytics Kyle Gesuelli said that it “feels like a better measure for us to just truly understand the underlying activity.”
Measured instead by cash paid by traders, the NFL’s share is smaller but shows the same climb: about half in Week 1, rising to 60% by Oct. 11.
The Commodity Futures Trading Commission (CFTC), the federal regulator that oversees prediction markets, requires exchanges like Kalshi and Polymarket US to publish daily trading volume as a count of contracts traded, the basis for notional volume. The NFL’s $3.3 billion total also lines up with notional volume.
In USA TODAY’s findings, the fastest-growing category was all-NFL combination bets, jumping from a 30% share on Sept. 13 to 45% on Oct. 11. A combo consists of multiple trades into one ticket, with every trade needing to be correct for the participant to win a payout.
Shane Kraus, an associate professor of psychology at UNLV whose specialty covers gambling addiction, warned that combos — a similar concept to parlay bets in traditional sports gambling — can encourage people to chase their losses, particularly when they narrowly miss a payout.
“That design is how they hook them,” Kraus said, describing the temptation to keep wagering after correctly predicting three or four outcomes in a five-leg parlay.
The fight over who regulates prediction markets
The NFL’s Supreme Court filing backs New Jersey regulators in a legal fight over whether sports contracts on prediction markets should be subject to state gambling laws.
Kalshi argues its contracts fall under the exclusive authority of the CFTC, while some states argue they amount to sports betting and should be subject to the same regulations as legal sportsbooks.
“The strongest argument the CFTC would have would be if the Supreme Court finds that the federal regulations preempt state law,” said John Holden, a business law professor at Indiana University’s Kelley School of Business. He added that protections common in state-licensed sports betting — “the self-exclusion list, the help numbers, things like that” — “aren't necessarily built into the federal regulations.”
Polymarket provided a statement to USA TODAY that said it “shares the NFL’s commitment to preserving the integrity of the game, which is why we’ve built advanced market surveillance tools and are actively collaborating with the CFTC, SEC, and other professional leagues toward a harmonized federal framework that delivers a stronger, more consistent form of integrity compared to a patchwork of disconnected state laws built for a bygone era.”
The regulatory battle regarding prediction markets is heating up beyond the Supreme Court, too — Kalshi has registered lobbyists in over 40 states, most of them since April, according to OpenSecrets.
A $59 billion month
Combined notional volume on Kalshi and Polymarket US grew from $2.83 billion on Sept. 13 to $4.6 billion on Oct. 11, a roughly 62% jump.
That jump is representative of the explosion Kalshi and Polymarket have experienced in 2026 so far.
In September 2026 alone, Kalshi’s notional volume reached $59.3 billion, according to digital-asset research and news site The Block, more than 20 times its $2.86 billion last September.
Sports drove much of that growth.
According to a Pew Research Center analysis of data from The Block, sports made up none of Kalshi’s trading volume in July 2024 and less than 3% of Polymarket’s trading volume. In July 2026, those shares were 78% and 82%, respectively.
Their rise can be felt in other places, too.
In a preliminary survey of 1,400 sports bettors, Kraus and his team found that 23.3% also used prediction markets, according to results shared with USA TODAY.
“Prediction markets came out of nowhere,” he said. “I think people who are doing sports betting are also doing prediction markets.”
Sportsbooks feel the squeeze
Meanwhile, as prediction markets soar, shares of some traditional sportsbook operators have fallen — DraftKings’ stock is down 44% since the start of the year, while Flutter, the parent company of FanDuel, is down nearly 65%.
DraftKings has moved into prediction markets itself, launching DraftKings Predictions in December 2025 and DKeX in June 2026. FanDuel Predicts also launched last December.
The moves put both DraftKings and Flutter in an unusual position: Their traditional sportsbooks face growing competition from prediction markets, even as they look to capitalize on the industry’s rapid expansion.
But with sports driving so much of that growth, Holden sees a more fundamental question about the industry’s future.
“The real question is, do these prediction markets exist without the sports products?” he said.
Chris Bumbaca contributed to this report.
This article originally appeared on USA TODAY: We tested the NFL's $1.8 billion prediction market claim. Is it true?