Americans Are Trading Billions of Dollars on Polymarket’s Banned Offshore Platform

Approximately 30 percent of the trading volume on Polymarket comes from the United States, according to a new study—an eye-popping number, considering that none of those people are legally allowed to use the crypto-based platform.

The study, conducted by Rutgers University statistician Harry Crane, estimated that people in the US funneled between $10.6 to $26.7 billion through Polymarket. To track the platform’s activity, Crane looked at what appeared to be US-based trades on offshore prediction market platforms from May 2025 to the end of April 2026. He found that many of the highest-volume markets on Polymarket were US-centric, including those covering US elections and sporting events. US-based traders appeared to participate on Polymarket’s sports vertical at especially high rates; the study estimated that they accounted for roughly half of the activity in those markets.

“It’s been known that there are individuals on there, but what hasn’t been known is the extent, whether it’s one or 10 or an actually appreciable fraction,” says Crane, who is also a member of the Commodity Futures Trading Commission Innovation Advisory Committee, a panel that offers federal regulators guidance on how technology impacts markets. The Coalition for Prediction Markets, a lobbying group on behalf of the industry, commissioned and funded the study, though Crane maintained editorial control. Kalshi, Coinbase, Crypto.com, and other major prediction market players are members of this group. Polymarket is not.

Polymarket is one of the most popular prediction markets in the world, allowing customers to trade on the outcomes of future events ranging from the winner of the NBA Finals to the price of bitcoin in five-minute increments to military actions in Iran. It has partnered with US-based media companies like Substack and Dow Jones, as well as American sports leagues like Major League Baseball and the National Hockey League.

But Polymarket’s primary crypto-based platform has been banned in the US since 2022, when federal regulators found that it had been operating as an unregistered derivatives trading platform. Since December 2025, Polymarket has operated a separate prediction market available on a mobile app that is licensed in the US, called Polymarket US. According to a report from Pew Research, Polymarket US’s trading volume in April 2026 came to around $1.6 billion, while the crypto-based primary platform hit around $9 billion, making it by far the larger marketplace.

Without reliable ways to directly observe site-traffic geography, Crane came up with a methodology