Prediction Markets Hit $14.1B in NFL Kickoff Week — Kalshi Holds 92% Market Share
Combined weekly volume across Kalshi and Polymarket reached $14.1 billion in the first full NFL regular season week (7-13 September). Kalshi held 92% of the combined total at $12.98 billion; Polymarket Global recorded $1.11 billion. Kalshi's NFL-specific volume hit $983 million for the week. Non-sports categories posted a sixth consecutive weekly record at $10 billion. Full-season NFL projection: $57 billion across all platforms.
Combined weekly contract volume across Kalshi and Polymarket Global reached $14.1 billion for the week of 7-13 September 2026 — the first full NFL regular season week — driven by football contracts, the US Open, Federal Reserve rate decision markets, and esports. Kalshi held 92.1% of the combined total at $12.98 billion. Polymarket Global recorded $1.11 billion. Kalshi's NFL-specific volume hit $983 million for the week alone, up 1,288% week-on-week. On the first Sunday of the NFL regular season, Kalshi saw $388 million in NFL game contracts — 76% of all NFL prediction market volume that day across platforms. DeFi Rate projects total NFL season volume across all prediction market platforms could reach $57 billion.
For UK readers, the scale reference point is the UK National Lottery, which turns over approximately £8 billion annually. Kalshi alone recorded $12.98 billion in a single week. The comparison is imperfect — lottery stakes and event contract notional volume are structurally different products — but it illustrates why the US states contesting Kalshi's legality view the commercial stakes as significant from a gambling tax and consumer protection perspective. The UK Gambling Commission's regulated market generates approximately £14 billion in gross gambling yield annually across all operators and products. The US prediction market sector is on a trajectory to produce comparable notional volumes in a single sport across a single platform in a single season.
Kalshi's 92% share of combined Kalshi-Polymarket volume is a significant shift from three months ago when the split was roughly equal. Three factors drive the divergence. First, Kalshi's perpetual futures products (crypto since May, gold and silver since September 10) generate large-notional non-sports volume at institutional scale. Second, Cantor Fitzgerald's broker network directs large block trades to Kalshi from approximately 3,000 institutional clients. Third, Kalshi's broader self-certified contract menu gives it more tradeable surface area than Polymarket US operates under the same CFTC framework. The non-sports weekly total reaching $10 billion — a sixth consecutive record — with Kalshi at $9.6 billion reflects this structural advantage in the non-sports categories that now dwarf sports contracts in volume terms.
The commercial magnitude of these volume figures is the essential context for the ongoing litigation. The states suing Kalshi and Robinhood are contesting access to markets running at $14 billion weekly. The CFTC's emergency orders protecting platforms in Michigan, New York, and other states are protecting a product that generates more notional volume in a week than many mid-size financial exchanges generate in a quarter. When the Ninth Circuit or eventually SCOTUS issues a definitive ruling on whether CFTC-licensed event contracts preempt state gambling law, that ruling will apply to a sector that has already scaled far beyond what any court or regulator was calibrating for when the litigation began.
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Recent updates
Missouri AG Sends Cease-and-Desist Letters to Six Prediction Market Operators
Missouri AG Catherine Hanaway issued cease-and-desist letters on September 18 to Kalshi, Polymarket, Robinhood, Crypto.com, Novig, and Underdog — the broadest single-state enforcement sweep yet. The letters give platforms 30 days to comply or obtain state gambling licences. Missouri alleges sports event contracts are unlicensed sports wagering. One day earlier, Montana agreed to pause its own Kalshi enforcement pending the Ninth Circuit en banc process.
Yahoo Finance Ends Polymarket Data Partnership After Five Months
Yahoo Finance and Polymarket ended their exclusive prediction market data partnership on September 18, five months after announcing it in November 2025. The dedicated Polymarket hub on Yahoo Finance was taken down in April 2026 after a two-month run. No reason disclosed. Yahoo Finance retains an advertising relationship with Polymarket. The partnership's failure is a setback for Polymarket's mainstream financial media distribution strategy.
Montana and Kalshi Reach Joint Stipulation — State Pauses Enforcement Pending Ninth Circuit En Banc
Kalshi dismissed its lawsuit against Montana on September 17 after both parties filed a joint stipulation in which Montana agreed to pause all enforcement pending the outcome of Kalshi's en banc petition at the Ninth Circuit. Montana must give 30 days notice before resuming once the en banc window closes. The agreement mirrors the Robinhood-Michigan stipulation of September 4 and reflects a pattern of negotiated appellate-linked pauses.