The New York Times: Founders at Odds? The Battle Between Kalshi and Polymarket is More Intense Than Expected

Original Title: Do These C.E.O.s Loathe Each Other? Bet on It.
Original Authors: David Yaffe-Bellany, William K. Rashbaum, The New York Times
Original Translation: Luffy, Foresight News

On a morning in November 2024, Shayne Coplan, founder of Polymarket, woke up to an unexpected visitor at his home. Several FBI agents burst into his New York apartment with a battering ram, searching for evidence related to illegal betting on the platform.

Coplan took to social media to claim that the search was a politically motivated crackdown initiated by the Biden administration. However, privately, he and his team had other suspects in mind, blaming many of Polymarket's troubles on their biggest competitor—the CEO of the prediction market platform Kalshi, Tarek Mansour.

Four insiders revealed that months before the FBI raid, Kalshi's lawyers had visited the Manhattan U.S. Attorney's Office to report issues related to Polymarket, a fact that had never been disclosed before. The insiders stated that the lawyers provided detailed information about Polymarket's operational model, highlighting a key issue: the platform should be prohibited for use in the U.S., yet users could still access it normally.

This confrontation is just the latest extreme conflict in the long-standing feud between Kalshi and Polymarket. Both are among the hottest startups in the tech industry today. The ambition clash between founders in Silicon Valley is not new; industry rivalries fueled by ego are common, much like the competition between Uber and Lyft in the ride-hailing market; the public feud between billionaires Sam Altman of OpenAI and Dario Amodei of Anthropic has also become a captivating subplot in the AI industry.

However, the rivalry between 28-year-old Coplan and 30-year-old Mansour has long surpassed the boundaries of normal business competition. Over forty insiders from both sides, who spoke anonymously, indicated that both are newly minted billionaires intent on monopolizing the prediction betting market across sports, politics, and entertainment, and they harbor extreme disdain for each other, a sentiment that permeates nearly all business interactions between their companies.

Shayne Coplan, Founder of Polymarket

Dustin Gouker, a long-time columnist on the prediction market industry, stated: "The animosity between the two has run too deep, and the conflict has long been mixed with personal grievances."

This battle has spilled over into internal company meetings, U.S. Congressional hearings, influencing regulatory policies in Washington, and has sparked unprecedented industry attention and regulatory concerns. The two companies have been competing for trademarks, vying for the same business partnerships, poaching each other's talent, publicly accusing one another in the media, and engaging in direct personal attacks on social platforms. Both have established business ties with Donald Trump, a common public relations strategy in Washington during his administration.

Noah Zingler-Sternig, a former Kalshi employee and prediction market fund manager, commented: "Both companies have crossed many lines, making it difficult for the public to take these two platforms seriously."

The hostility between them is not just a battle for market share; deeper differences lie in their ethical standards and business practices. Kalshi has cultivated an image as a compliance benchmark, insisting on obtaining U.S. regulatory approval before launching domestic operations; Polymarket, on the other hand, has operated offshore for a long time without a domestic license. Kalshi strictly enforces real-name verification rules and blocks sensitive betting categories; Polymarket allows users to register without submitting personal information, even permitting bets on events like the timing of missile strikes in Israel.

Over the years, Coplan and Mansour have crossed paths, but now they hardly interact, only disparaging each other from a distance. Mansour, a graduate of MIT and a self-proclaimed math enthusiast, has compared their competition to that of Tom Brady and Eli Manning, two legendary quarterbacks in healthy competition. However, recently, he has bluntly stated that Polymarket's operational model is "illegal and unethical," pointing out that its offshore platform is operated by a Panamanian entity.

In April of this year, Mansour publicly stated at an industry conference in Washington: "I don't know what regulations Panama has regarding insider trading in prediction markets, but it's highly likely there are no relevant constraints."

Coplan, who dropped out of New York University and is skilled at generating buzz, rarely mentions Kalshi in public. However, two insiders revealed that he privately claims Kalshi merely copied Polymarket's model and believes Mansour has been trying to suppress him. Coplan firmly believes that his platform is the best solution in the industry, stating on the show 60 Minutes last year: "This is the most accurate information tool currently available to humanity."

Kalshi spokesperson Elisabeth Diana stated that the company learned about the FBI search through news reports. She added that Kalshi regularly communicates with regulatory agencies regarding compliance issues and has publicly pointed out that "some companies harm user rights and damage the industry's reputation."

Tarek Mansour, Co-founder of Kalshi

Diana stated, "Mansour has no personal animosity towards Shayne; his only dissatisfaction is that Kalshi has spent years promoting industry compliance while the other operates without any ethical boundaries."

A Polymarket spokesperson responded to Mansour by quoting a saying from Emerson: "Those who boast of their high moral character should watch their own silver spoon." They also stated that the platform has established a comprehensive insider trading screening mechanism, having referred suspicious leads to law enforcement nearly a hundred times, and emphasized: "We are committed to creating an accurate, fair, and transparent trading market."

As prediction markets transition from niche to mainstream, the regulatory pressure facing both companies continues to rise. Attorneys General from multiple states across the U.S. have filed lawsuits against both platforms, accusing them of violating regulations in their betting operations; Polymarket is also under investigation by the Commodity Futures Trading Commission (CFTC).

Kalshi's reports against Polymarket have become increasingly direct. In May, former CFTC commissioner and current Kalshi board member Brian Quintenz posted on X, detailing Polymarket's user review mechanism and tagging the official account of the U.S. Attorney's Office for the Southern District of New York.

The History of the Rivalry Between the Two Competitors

Coplan is a native New Yorker who founded Polymarket in 2020, initially operating out of an apartment in downtown Manhattan, with a bathroom temporarily converted into an office and a laptop as the only equipment. At that time, he considered himself a newcomer to the industry, pioneering a completely non-mainstream product.

He quickly faced a strong competitor. Mansour grew up in Lebanon and was a trader at Fortress Investment Group; in 2018, he co-founded Kalshi with his MIT classmate and current COO Luana Lopes Lara. Colleagues describe Mansour as intelligent and daring, though somewhat reserved; Coplan is easygoing, collects art, loves music, and embodies the relaxed and carefree demeanor of a New Yorker.

Luana Lopes Lara, Co-founder of Kalshi

The relationship between the two has never been very friendly. Insiders recall an awkward early meeting where Coplan mentioned that both were raised by single mothers, which made Mansour quite uncomfortable.

However, they share a common belief: prediction markets will reshape the financial and media industries, producing highly valuable information references through "collective intelligence." Both Polymarket and Kalshi present bets in the form of "yes/no" questions, covering events such as weather and the Super Bowl. The total amount of user bets determines the odds for corresponding events.

Kalshi applied for a full operating license from the CFTC before launching its betting business in 2021. Three insiders revealed that during the initial communication phase with regulators, Kalshi had already reported compliance issues related to Polymarket.

The main contact person was Kalshi's strategic advisor Jeff Bandman, who repeatedly urged the CFTC to investigate Coplan's company, pointing out that the platform could be used in the U.S. without permission. In January 2022, regulators fined Polymarket $1.4 million and ordered the platform to cease accepting bets from U.S. users.

This ban once gave Kalshi the hope of monopolizing the U.S. domestic market, but the company still needed to negotiate with regulators for more lenient operating rules. During the Biden administration, the CFTC prohibited election-related betting, and Kalshi sued the regulatory agency in 2023.

During Kalshi's legal troubles, even though Polymarket was banned from serving U.S. users, it continued to thrive. U.S. users could access the offshore site by using a virtual private network to change their location. Before the 2024 presidential election, the platform's odds sparked widespread discussion online, showing that the probability of Trump winning was significantly higher than traditional polls.

In June, Mansour stated on a podcast: "They completely skipped the compliance process and launched products without any scruples."

As the election approached, Kalshi won in court, allowing licensed prediction markets to operate legally in the U.S. Polymarket still lacks domestic operating qualifications, but its platform traffic surged, and Coplan became an industry celebrity.

In 2024, the Southern District Attorney's Office in New York launched an investigation to verify whether Polymarket had violated regulations by offering services to U.S. users. A week after Trump's victory, the FBI raided Coplan's Manhattan apartment, seizing all electronic devices.

Kalshi immediately seized the opportunity to create buzz. Tech media outlet "Pirate Wires" revealed chat screenshots showing Kalshi employee Keaton Inglis contacting former NFL star Antonio Brown, instructing him to post on X platform claiming Coplan was "guilty."

Antonio Brown, former NFL star

Brown later apologized, stating he was in a business partnership with Kalshi at the time and had casually shared the content. Mansour also apologized, stating in a December 2024 podcast, "Some of our team members were overly emotional at that time."

The raid left Coplan and his team suspicious, and related rumors quickly spread through the media. Four insiders revealed that there was private speculation within Polymarket that Kalshi or its partners had hired private investigators to track Coplan, who immediately tipped off the media after encountering the FBI.

Kalshi spokesperson Diana refuted this, saying, "This is completely absurd; their imagination has reached ridiculous levels."

### Sabotaging Major Collaborations
In July last year, Coplan attended a crucial business dinner at the top-floor restaurant Manhatta in Manhattan, which boasts a panoramic view from the 60th floor. He dressed casually, carrying a bagel in a paper bag.

The other party at the dinner was billionaire Jeffrey Sprecher, founder of the Intercontinental Exchange. This $80 billion giant operates the New York Stock Exchange. The meeting between the titans of old and new industries marked a critical turning point in the competition between Polymarket and Kalshi.

For years, Kalshi has had top-tier venture capitalists like Sequoia Capital backing it; Coplan had repeatedly faced obstacles in securing funding from large institutions. However, both Coplan and Mansour were vying for investment from the Intercontinental Exchange, which was interested in entering the prediction market space.

Coplan and Sprecher hit it off. The Intercontinental Exchange had initially considered investing in Kalshi but ultimately finalized an investment agreement with Polymarket last fall.

Insiders say Mansour was furious upon learning the news. Five insiders revealed that before the official announcement of the collaboration, Mansour had separately met with Alex Immerman, a partner at Kalshi's investor a16z, to discuss the Intercontinental Exchange's executive team.

While several insiders provided differing details about the conversations, three confirmed that Mansour's communication with Immerman was essentially an attempt to persuade the Intercontinental Exchange to abandon the investment.

Kalshi spokesperson Diana stated that the company had "no intention of pursuing a partnership with Sprecher."

Jeffrey Sprecher, founder of the Intercontinental Exchange

Ultimately, Sprecher chose to bet on Coplan, announcing a maximum investment of $2 billion in Polymarket in October. This was just one of the favorable developments for Polymarket: in July last year, the Trump administration tightened enforcement, and the Southern District withdrew its investigation into Coplan; that summer, 1789 Capital, a venture fund under Donald Trump Jr., also announced an investment in Polymarket.

Coplan stated in a "60 Minutes" interview last year, "This administration strongly supports innovation and the crypto industry, especially Polymarket, which is very rare."

To seize the policy dividends, Polymarket must obtain an operating license in the U.S. Coplan plans to acquire a company that already holds compliance qualifications.

He once again encountered Kalshi's obstruction. Five insiders revealed that rumors circulated that Coplan intended to acquire the niche prediction platform Railbird, prompting Mansour to report potential risks related to the acquisition to senior officials at the CFTC.

Kalshi's report was ineffective, and in June 2025, the CFTC approved Railbird's operating qualifications. Coplan ultimately spent $112 million to acquire another licensed company, QCX. Although the offshore main platform remained restricted, after acquiring QCX, Polymarket launched a lightweight version of its app for the U.S. market, allowing it to reach a vast number of local users.

When announcing the acquisition in July, Coplan posted a picture of the American flag on social media with the caption, "I have waited too long for this day; Polymarket is officially returning to the U.S."

### Deliberate Provocation in Business Rivalry
This spring, as the New York Knicks made it to the playoffs, Mansour posted photos of himself watching the game at Madison Square Garden, wearing team colors and grinning widely.

Officially, this was a celebration of Kalshi's new partnership with the arena, with the sixth-floor corridor officially named the Kalshi Corridor. However, industry observers saw another layer of meaning: a deliberate provocation.

Before Coplan's rise, he frequently shared Knicks-related content on social media and was often seen courtside during regular-season games. Insiders revealed that before finalizing the partnership, Kalshi had also discussed similar sponsorships with Polymarket but was unwilling to match the offer made by Kalshi.

This also marked a shift from an industry conflict limited to the niche crypto circle to the public eye. In the first six months of this year, the total transaction volume of the two platforms exceeded $150 billion, a 1200% increase, undoubtedly intensifying the competition.

From current data, Mansour is temporarily in the lead. After completing a new round of financing in May, Kalshi's valuation reached $22 billion, $7 billion higher than Polymarket. Data agency The Block reported that last month, Kalshi's transaction volume was $33 billion, double that of Polymarket.

Diana denied that the collaboration with Madison Square Garden was aimed at targeting Coplan: "We would not finalize a business partnership just to provoke a competitor; that claim is ridiculous."

The surge in popularity of prediction markets has also attracted stricter regulatory scrutiny, with most of the focus falling on Polymarket. In April this year, a U.S. Army Special Forces soldier was indicted for using classified information to log into Polymarket's offshore platform via VPN to bet on the arrest of Venezuelan President Maduro, illegally profiting over $400,000. A Polymarket spokesperson stated that the platform strictly prohibits VPN access.

The two platforms have entirely different approaches to controlling insider trading. Kalshi requires users to submit complete personal information before placing bets, and in some cases, they must report their occupation; Polymarket's transactions are all publicly available on the blockchain, allowing community users to self-check for violations. U.S. app users must undergo real-name verification, but the offshore main platform still does not require users to disclose personal information such as names or workplaces.

Polymarket's paid influencer Aj Pleasanton commented that this model is quite common in the crypto industry, and users generally prefer to operate anonymously.

Privately, Mansour has grown increasingly dissatisfied with Polymarket's operating model. Two insiders revealed that he frequently called Polymarket's Chief Legal Officer Neal Kumar to express his anger.

Conflicts between the two parties have been frequent. According to documents reviewed by insiders and The New York Times, in the spring of 2025, several influencers contracted with Polymarket spread rumors about the breakdown of Kalshi's collaboration with Elon Musk's xAI.

In the same year, Polymarket hired early Uber employee Max Crowley as Vice President of Partnerships, but less than two months after joining, Crowley switched to Kalshi, which infuriated Coplan. Insiders say that during the transition, Coplan and the company's board attorney Alex Spiro sent a lawyer's letter threatening to sue, but ultimately did not file a case.

Even with shared industry demands, the two companies refuse to collaborate. Kalshi has formed an industry lobbying group to combat restrictive regulations on prediction markets introduced by various states, uniting several peers while excluding Polymarket.

The following month, Kalshi faced a setback in a sports betting lawsuit in one state, and Polymarket immediately launched a new betting target, opening bets on the timeline for Kalshi's Massachusetts sports business shutdown.

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