The NFL has asked prediction market platforms to remove markets considered vulnerable to manipulation and those whose outcomes may be known in advance.
ESPN reports that the league sent letters to Kalshi and Polymarket over the last weekend, marking an effort to exert more influence over the emerging wagering models.
The request included several types of trades that are considered vulnerable.
Among them are markets that may be influenced by an individual, such as a missed field goal, and those that may be known in advance by relevant people, such as draft picks, player moves, and coaching changes.
The NFL likewise opposes markets involving officiating decisions, as well as issues that are inherently objectionable, such as player injuries and issues concerning fan safety.
Officials explained that the aim of this measure is to protect participants from allegations associated with gambling activity.
This, in essence, is a further attempt to deal with sports integrity and reputational risk as prediction markets become more mainstream alongside traditional sportsbooks.
While other leagues, including MLB, the NHL, UFC, and MLS, have entered into partnerships with prediction market operators, the NFL has so far adopted a more cautious posture.
Its latest communication extends beyond previous sportsbook guidance by also addressing novelty-style markets that go beyond on-field outcomes, including mention markets on commentary during broadcasts, and celebrity attendance.
Football means big business for prediction markets
Kalshi’s transaction-based model generated substantial revenue during the 2025–2026 NFL season, with total annual revenue reaching $260m.
Sports trading accounted for 89% of that figure. Activity surged between September and November, producing $138m in fees tied to NFL markets alone.
During the Super Bowl LXI period, Kalshi processed $10.44bn in monthly volume, including $871.5m on Super Bowl Sunday, generating approximately $10.4m in revenue in a single day.
Excluding the Super Bowl, Kalshi’s NFL-related revenue is estimated at around $180m, supported by late-season spikes where weekly fees reached $20m.
The platform also expanded into novelty markets, including on halftime shows and commercials, which contributed to higher engagement among US-based traders.
Polymarket, by contrast, operated without fees for most of the season despite handling significant trading volume. Its sports-related activity reached roughly $4bn monthly, with total NFL volume exceeding $1bn.
On Super Bowl Sunday, it recorded $311.9m in trades. However, revenue remained effectively zero until the company introduced a probability-based taker fee on 30 March, a change expected to generate about $1m per day in revenue.