Polymarket, Kalshi turn rivalry into a Washington lobbying war

The two biggest US prediction markets are no longer just competing on trading volume, they are running full DC playbooks against each other. The New York Times reports that Polymarket CEO Shayne Coplan and Kalshi's Tarek Mansour have escalated their rivalry into lobbying pushes, ad blitzes, and internal dossiers of alleged copying.

The most vivid piece is a document Polymarket internally calls 'copycat', which reportedly logs roughly a dozen eyebrow-raising incidents where Kalshi launched products that looked strikingly like Polymarket's, with suspicious timing. One example cited: on June 10 last year Webull announced it would launch Kalshi's hourly crypto markets, and the same day Polymarket announced its own. Suspicions inside Polymarket hardened in February, when a team was preparing a Feb. 12 pop-up grocery store in lower Manhattan branded 'Polymarket', backed by a $643,380 lease covering branding and production for the five-day event. Some Polymarket employees have also raised concerns that Paradigm, the venture firm that backs Kalshi and rents Soho offices directly across the street, could be watching. Paradigm called the accusation 'laughable', and Kalshi spokesperson Jack Such called it 'sad and borderline delusional'.

The Washington fight is the more consequential half. Kalshi spent $615,000 on lobbying in 2025 to Polymarket's $360,000 and rolled out a mint-green ad campaign across billboards, bus shelters and Washington Post inserts, according to CNBC's reporting on the same rivalry. Kalshi co-founder Luana Lopes Lara wrote to CFTC Chair Mike Selig on April 30 asking him to crack down on Polymarket for not doing enough to block US users from its unregistered international exchange. The CFTC's subsequent rule proposal for exchange betting made no mention of that ask, and House Oversight Chair James Comer has since opened his own probe into both companies.

The honest caveat is that most of the copycat and spying claims trace back to one side of the story, and the reporting does not settle whether any of it is legally actionable or how the House Oversight probe will land. What the reporting does make clear is that prediction markets have crossed from novelty into regulated infrastructure worth fighting over in DC, and the operator that wins the Washington argument, not just the trading argument, is the one the next wave of data buyers and product integrators will end up building on top of.