Polymarket Builds Copycat Dossier on Kalshi and Follows Suit in Minnesota Legal Fight
The rivalry between Polymarket and Kalshi has escalated. Polymarket compiled a dossier documenting instances where it alleges Kalshi stole ideas. At the same time Polymarket followed Kalshi by filing a lawsuit against the state of Minnesota.
Both companies face regulators who target prediction market platforms as illegal gambling operations. Their fates appear interlinked. Yet there is no love lost between these two New York-based businesses.
Polymarket now accuses Kalshi of spying on its offices. After eighteen years across iGaming and sportsbook operations the pattern feels familiar. When two platforms chase the same users the edges get sharp fast.
Accusations of Spying Across the Street
Polymarket’s office sits across from a building leased by Paradigm. That venture capital firm invested in Kalshi. Employees allege Kalshi could use the space to spy through the windows.
One employee said the team discussed whether it was possible. They concluded that with Kalshi it is. Paradigm dismissed the claims as laughable. Kalshi spokesperson Jack Such called them sad and borderline delusional.
Such added that Polymarket is welcome to waste time investigating while Kalshi keeps building. The exchange highlights how heated the competition has become. From the supplier side this kind of finger-pointing rarely ends with a clean resolution.
Grocery Promotions and Suspicious Timing
The spying talk followed Kalshi’s launch of a free grocery campaign. Kalshi announced the promotion on February 2. Polymarket had been planning its own grocery pop-up store for months.
Polymarket announced the next day. It signed the lease and donated $1 million to Food Bank For NYC. A Polymarket insider said Kalshi seemed to know the announcement timing. To them the timing was suspicious.
Shayne Coplan, Polymarket’s founder and CEO, has called Kalshi a copycat site. Tarek Mansour, Kalshi CEO, responded that the acquisition of QCEX by Polymarket was super normal for competition. The back and forth shows how each side views the other’s moves.
Matching Product Launches and Ad Campaigns
On June 10 last year Webull announced it would launch Kalshi’s hourly crypto markets. The same day Polymarket announced its own hourly crypto markets. Polymarket alleges the timing is suspicious.
“Kalshi has offered these products since well before June 10, 2025,” said Such. “That was just the day that Webull started to offer them. The fact that Polymarket announced this product long after we had actually launched should make it obvious who is copying whom.”
Both companies ran ad campaigns targeting states where sports betting is illegal. Polymarket began advertising in California on Friday, August 22, 2025, for soccer matches with the Hey California tagline. Kalshi launched its California campaign three days later with the same tagline.
Such called any espionage claim delusional. He noted Polymarket holds no trademark over the extremely common phrase. These parallel moves in ads and product timing fuel the dossier Polymarket compiled.
Shared Legal Battles and Regulatory Pressure
The campaigns aimed at states without legal sports betting have triggered legal fights nationwide. Polymarket this week followed Kalshi in suing Minnesota after the state approved a ban on prediction markets.
“When it goes into effect in less than two months, Polymarket US will face a credible threat of imminent criminal prosecution—forcing it either to cease lawful and constitutionally protected conduct or risk felony criminal liability,” states the lawsuit. The CFTC also sued Minnesota claiming exclusive jurisdiction over prediction markets.
Both Kalshi and Polymarket hold CFTC licenses. Their regulatory fights run in parallel. Yet the companies show no willingness to assist each other.
Risks and Counterarguments in the Rivalry
The spying and copycat claims carry real risks for both platforms. Public accusations can damage trust with users and partners at a time when regulators already view prediction markets skeptically. If the claims escalate without evidence they could invite closer scrutiny from the very authorities both companies are fighting in court.
On the other side Kalshi’s responses frame the allegations as distractions from actual product building. The counterpoint has merit. Timing coincidences happen in competitive markets especially when both firms target the same underserved states and user behaviors. Dismissing every overlap as espionage risks sounding exactly as Such described it.
From an operator perspective the real limitation is distraction. Eighteen years in the space taught me that energy spent on dossiers rarely moves the P&L. The shared Minnesota fight and CFTC alignment matter more for long-term viability than who announced groceries first.
The Bottom Line
This feud between Polymarket and Kalshi mixes personal rivalry with identical regulatory headwinds in Minnesota and beyond. The dossier and spying claims add color but the real story sits in how both platforms navigate the same legal threats while chasing identical users. Industry executives should watch whether the public sniping weakens their joint regulatory arguments or simply sharpens each company’s execution. The next few months of litigation will test which approach actually wins market share when the bans hit.
