Prediction markets went absolutely parabolic last quarter. Kalshi and Polymarket just posted record-shattering numbers in the third quarter of 2025, with over $3 billion in notional volume, more than five times what they saw this time last year.
The mania has topped even the madness of the 2024 US presidential election, and the surge has Wall Street’s CME Group and Intercontinental Exchange pushing their way in. According to data from Bloomberg, both platforms crossed $2 billion in the week ending October 19, the most they’ve ever seen.
The rally was mainly driven by a wave of sports betting, mostly through New York‑based Kalshi, which used its federal license to offer bets nationwide, ignoring state gambling regulators.
Kalshi’s contract volumes surged after football season kicked off in August and September, and users flooded in, especially retail traders from Robinhood, thanks to a new partnership.
On the other side, Polymarket, still closed to US traders after infamous fights with regulators, saw a similar jump in traffic as crypto degens and political bettors found new events to bet on.
Kalshi leverages Robinhood crowd as football spikes trading
Football bets dominated the week of October 19, pulling in $867 million on Kalshi and $415 million on Polymarket.
Kalshi gained an edge by offering parlays, allowing users to bet on several low-odds events at once. In prediction markets, every contract pays either $0 or $1 when the event ends.
Dune Analytics user dunedata tracked the public numbers, counting only one side of each trade to make the two exchanges comparable. Kalshi’s data came from its own filings, which spokesperson Claire McManus confirmed were accurate. Meanwhile, Polymarket’s data was gotten from its public blockchain, after Rachel Lowe, speaking on behalf of the team, called the data there “the best available publicly,” while adding that there are “always nuances to it.”
The last time volumes were this high was during the 2024 presidential election, when Kalshi won a court case against the Commodity Futures Trading Commission. That win let Kalshi legally host contracts on the election outcome.
Both Kalshi and Polymarket had bettors giving Donald Trump high odds of winning. Since his return to the White House, Trump and his circle have thrown their weight behind the industry. His son, Donald Trump Jr., now serves as an adviser to both platforms.
Polymarket reclaims lead as ICE and CME pile in
In August, Kalshi briefly overtook Polymarket in overall trading volume thanks to sports. But Polymarket snatched back the lead last week after doubling its sports-related volume. While Kalshi rode a regulated edge in the U.S., Polymarket stayed outside the country due to previous legal clashes.
That’s changing. Polymarket just bought QCX, a CFTC‑licensed derivatives exchange, a move that sets them up for a return to the U.S. market.
Wall Street wants in. ICE, the owner of the New York Stock Exchange, invested $2 billion for a stake in Polymarket. CME Group is now planning to roll out contracts tied to sports games. These moves are coming even as DraftKings and FanDuel-owner Flutter Entertainment see their shares slide.
Their platforms still depend on state-by-state gambling licenses, while Kalshi’s federal license gives it wider access, though not without heat.
Several state regulators are now trying to shut Kalshi down, saying its bets violate state gaming laws. Kalshi is fighting those cases in court. As McManus put it, “We’re federally regulated. That’s what matters.”
On October 18, during a rush of college football bets, users trading on Kalshi reported platform issues. McManus admitted the site faced “data loading delays due to extreme demand” but said trading continued on the backend without disruption. She added that the issue was resolved quickly.
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