Two Polymarket users have sued the prediction market platform in New York state court, claiming the company changed the rules of a Bitcoin-related market after the underlying event had already happened and wrongly denied payouts to traders who correctly predicted the result.

The complaint, filed in the Supreme Court of the State of New York, names Adventure One QSS Inc., doing business as Polymarket.com; Blockratize Inc., doing business as Polymarket; Chief Executive Officer Shayne Coplan; Chief Marketing Officer Matthew Modabber; and additional unnamed defendants.

According to the lawsuit, plaintiffs William Wood and Thomas Bush bought “Yes” shares in a market asking whether Strategy Inc., formerly MicroStrategy, would sell any of its Bitcoin holdings by May 31, 2026. They point to a Form 8-K filed with the U.S. Securities and Exchange Commission stating the company sold 32 Bitcoin during the relevant period, arguing that outcome meant the market should have resolved as “Yes.”

Bitcoin market dispute adds to Polymarket legal challenges

Instead, the complaint says Polymarket settled the market as “No” after adding clarification language that shifted the question from whether Strategy sold Bitcoin before the deadline to whether the sale had been publicly confirmed by that date. The plaintiffs argue the sale itself was the event participants were predicting, while the SEC filing merely documented that it had already occurred.

The lawsuit describes the disagreement as involving an objective and verifiable fact rather than an ambiguous prediction. It further argues that changing the governing standard after the event undermined the platform’s promise that markets are resolved using fixed, pre-defined rules. The plaintiffs also cite Polymarket’s marketing, including statements that users can “profit from [their] knowledge” and that its markets “seek truth,” alleging those representations influenced their trading decisions.

The filing also contends Pol...