Non-sports event-contract volume just set another record, and the split is no longer close. Combined activity across Kalshi and Polymarket reached $10 billion in the week ending September 13, the sixth straight week at that level in that slice of the order book. Kalshi took $9.6 billion. Polymarket was left with $344.2 million, or about 4% of the category.
That gap would have sounded implausible a year ago, when Polymarket still led in non-sports events. Three months ago, the two venues were still near 50/50. Retail brokerage rails explain most of the swing: Kalshi contracts now sit inside accounts traders already fund for stocks and options.
How Weekly Non-Sports Share Flipped So Fast
The reversal did not happen in one sudden move. By early June, the split had evened out. After that, Kalshi’s share kept climbing until the latest week left almost no room on the other side of the chart.
Kalshi contracts now trade on Robinhood, Coinbase, Webull, and Moomoo. One-third of Kalshi’s daily flow arrives through Robinhood alone. Traders don’t have to open a new wallet before clicking into a new federally regulated contract or an hourly index market. They can trade on these prediction markets as they do stocks, right on the same screen.
Polymarket’s US-based CFTC-regulated venue, built after the July 2025 purchase of exchange-and-clearinghouse QCEX for $112 million, still settles differently from its original on-chain, offshore book. This has allowed Polymarket US to explore similar regulated market deals that Kalshi has been pursuing for some time. But they are behind the eight ball. The Polymarket US app only became fully available on the Apple Store this past May.
Non-sports flow is no longer a rounding error for Kalshi. Year-to-date trading volume for Kalshi non-sports markets is estimated between $18 billion and $36 billion. While sports still dominates their total volume, this non-sports number is on a fast-growing trajectory and already quite sizable. This could put Kalshi’s non-sports trading revenue at about $500 million thus far in 2026.
Hourly Contracts Turned the Book Into a Turnover Machine
Product design is amplifying Kalshi’s brokerage edge. Kalshi lists hourly contracts on the S&P 500, Nasdaq, Bitcoin, and Ethereum. Each contract expires and is replaced within 60 minutes, so the same cash can recycle many times in one session.
Longer-dated Federal Reserve markets for late October and December keep the order book from going quiet between those short bursts. Together, the short clock and the long clock produce a cadence closer to listed futures than to a one-off election forecasting board with its seasonal event-based patterns.
That mix is why the non-sports column on Kalshi can swell even when politics is not dominating the news. Hourly crypto and index contracts also clear nearer mid-price than long-shot parlays, so notional volume stacks quickly.
Artemis dashboards’ industry data on prediction markets leans on on-chain activity for part of the Polymarket read, and the regulated onshore venue does not settle that way. Some U.S. flow therefore sits outside the $344.2 million figure they’ve assigned Polymarket. The gap is still huge.
A License Lists the Contract. An App Icon Gets It Traded.
The Commodity Futures Trading Commission treats event-contract derivatives as its turf. Both Kalshi and Polymarket’s regulated venue operate under that oversight. Kalshi secured a license first and used the head start to approach Wall Street brokerage firms with integrated access to prediction markets.
Sports markets do. tell a different story. Polymarket reached about 43.8% of Kalshi’s football volume within months of a late-2025 U.S. sports push. The difference likely reflects sports event traders more freely choosing platforms, switching, and testing what they prefer, as they did with sports betting apps. Channels like brokerage house integration require long-term commitments and present greater obstacles to short-term switching.
Kalshi and Polymarket posted global volume of $14.10 billion for the week of September 7–13, with Kalshi taking $12.98 billion and a 92.1% share. Kalshi’s September month-to-date volume through September 13 had already reached $23.45 billion, 53.4% above the same stretch in August.
DeFiLlama Research had already shown Kalshi pulling ahead on a durable basis after mid-April, with sports and crypto-price markets doing most of the work. Polymarket’s public Dune overview still shows large lifetime volume across its DeFi and U.S. books. Lifetime scale isn’t the same as this week’s non-sports split.
References
- FinanceFeeds, “Kalshi Takes $9.6B of $10B Weekly Prediction Market Volume”
- CryptoNews.net / Cryptopolitan, “Non-Sports Prediction Market Volume Hits $10 Billion”
- CoinLaw, Prediction Market Statistics
- Artemis, Prediction Markets sector dashboard
- Commodity Futures Trading Commission
- CryptoBriefing, Polymarket football share versus Kalshi
- DeFi Rate, $14.1B weekly volume report
- ReadWrite, Kalshi 92.1% weekly share
- DeFiLlama Research, “Are Prediction Markets Still Hot?”
- Dune, Polymarket Overview
