Polymarket and Kalshi are fighting for attention in the fast-growing prediction markets sector, and the latest dispute now includes claims of copying, office spying, and leaked product timing.
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Polymarket has accused Kalshi of going beyond normal competition after several launches and marketing campaigns landed close to Polymarket plans, according to a New York Post report. The New York based prediction market operator, founded by Shayne Coplan, has kept an internal file with screenshots of ads, product designs, social posts, and announcements it believes show copying.
Matthew Modabber, Chief Marketing Officer at Polymarket, told the New York Post:
“There have been too many coincidences. There is bad intention in how they copy us. They’re breathing down our neck.”
The complaint goes further than similar ads. Polymarket sources told the outlet that Kalshi moles could be inside the company office. Staff also raised concern about Paradigm, the venture capital firm across the street from Polymarket. Paradigm has invested in Kalshi.
Polymarket reportedly tinted office windows after concerns that computer screens could be viewed from nearby space on behalf of Kalshi. Both Kalshi and Paradigm denied the claim.
Kalshi spokesperson Jack Such told The Post:
“This is sad and borderline delusional. Polymarket is welcome to waste its time investigating. While they do that, we’ll keep building.”
The sharpest example came from a New York grocery campaign. Polymarket planned to give free groceries to 300 customers in Manhattan, an event tied to Coplan and his New York roots. Nine days before that event, Kalshi ran its own grocery promotion with $50 vouchers and a market tied to rising egg prices. Business Insider also reported on the two grocery stunts in February, noting Kalshi ran its one-day event before the longer Polymarket pop-up and that Polymarket donated $1 million to Food Bank For New York City.
Elizabeth Diana, head of information at Kalshi, told The Post that Kalshi had worked on its grocery promotion for a long time and did not copy Polymarket.
Product timing has also become part of the fight. Polymarket sources said the company planned to launch perpetual trading on April 21. One hour before the launch, a report said Kalshi was also preparing trading on “perps.”
A Polymarket insider told The Post:
“They seemed to know we were going to announce that day. To us, the timing was pretty suspicious.”
The rivalry now sits inside a much wider fight over prediction markets, sports event contracts, and state gaming rules. The CFTC recently sued Minnesota over a new law that would ban platforms such as Kalshi and Polymarket from operating, hosting, or promoting prediction markets in the state from August 1, 2026. The agency argues those contracts fall under federal derivatives law, while Minnesota officials say the law protects consumers from gambling harm.