《The New York Times》: Founder Feud? Kalshi and Polymarket Business Rivalry Much More Intense Than Anticipated

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 November morning in 2024, Polymarket founder Shayne Coplan woke up to an unexpected visitor in his home. Several FBI agents broke into his New York apartment with a battering ram, conducting a search for evidence related to the platform's illegal gambling activities.

Coplan took to social media to claim that the raid was a politically motivated crackdown by the Biden administration. However, privately, he and his team suspected a different culprit and attributed many of Polymarket's troubles to their primary competitor — Tarek Mansour, the CEO of the prediction market platform Kalshi.

Four sources familiar with the matter revealed that months before the FBI's raid, Kalshi's lawyers had visited the Manhattan U.S. Attorney's Office to report issues related to Polymarket, a matter that had not been previously disclosed. The sources stated that the lawyers provided prosecutors with a detailed overview of Polymarket's operations, emphasizing a key concern: while the platform should be off-limits in the U.S., users could still access it.

This standoff is just one extreme clash in the long-standing rivalry between Kalshi and Polymarket. Both are currently the hottest startups in the tech industry. Ambitious clashes between Silicon Valley founders are not uncommon, and industry battles fueled by arrogance are ubiquitous, such as Uber and Lyft's competition in the ride-hailing market. In another example, OpenAI's Sam Altman and Anthropic's Dario Amodei, two AI billionaires, engaging in a public feud have become a noteworthy subplot in the AI industry.

However, the rivalry between the 28-year-old Coplan and the 30-year-old Mansour has long exceeded the boundaries of normal business competition. Over forty insiders from both sides, speaking on condition of anonymity, stated that the two newly minted billionaires are singularly focused on monopolizing the predictive betting market across all categories including sports, politics, and entertainment. They harbor a deep mutual animosity, and this antagonistic sentiment permeates nearly all interactions between the two companies.

Shayne Coplan, Founder of Polymarket

Long-time columnist writing about the prediction market industry, Dustin Gouker, stated: "The two sides have deep-seated grievances, and the conflict has long been intertwined with personal vendettas."

This feud has spread to internal company meetings, U.S. congressional hearings, influencing Washington's regulatory policy direction, triggering unprecedented industry attention and regulatory concerns. Both companies have clashed over trademark registrations, fought over the same business partnership, poached each other's talent, publicly accused each other in the media, and engaged in direct personal attacks on social platforms. Both have also established business partnerships with former President Donald Trump, a common public relations strategy within the Washington circles during the Trump administration.

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

The hostility between the two goes beyond a market share battle, with deeper disagreements on ethical conduct and business practices. Kalshi has portrayed itself as a compliance benchmark, insisting on obtaining U.S. regulatory approval before conducting domestic operations; meanwhile, Polymarket has not obtained a domestic license and has operated its core platform offshore for an extended period. Kalshi strictly enforces real-name verification rules and blocks sensitive betting categories; on the other hand, Polymarket users can register without providing personal information and can even bet on events like the timing of an Israeli missile attack.

Although Coplan and Mansour have crossed paths over the years, they now have almost no communication and only engage in public defamation of each other. Mansour, a graduate of MIT who identifies as a math enthusiast, once likened the competition between the two to Tom Brady and Eli Manning, two legendary quarterbacks engaged in friendly competition. However, recently, he bluntly stated that Polymarket's operating model is "illegal and unethical," pointing out that its offshore platform is operated by a Panamanian entity.

In April of this year, at an industry conference in Washington, Mansour openly stated: "I don't know what regulations Panama has regarding insider trading in the prediction market, most likely there are no relevant constraints."

Having graduated from New York University and excelling in public appearances, Coplan rarely mentions Kalshi in public. However, two insiders revealed that he privately believes Kalshi simply copied the Polymarket model and is convinced that Mansour has been actively trying to suppress him. Coplan firmly believes that his platform is the best solution in the industry and declared on a CBS "60 Minutes" program last year: "This is the most accurate information tool humanity currently possesses."

Elisabeth Diana, a spokesperson for Kalshi, stated that the company only learned about the FBI search through news reports. She added that Kalshi regularly communicates with regulatory agencies on compliance issues and has publicly pointed out that "there are companies harming user rights and damaging the industry's reputation."

Tarek Mansour, Co-founder of Kalshi

Diana stated, "Mansour himself has no personal animosity towards Shayne; his only grievance is that Kalshi has spent years advancing industry compliance, while the other party operates the race track in a bottom-line manner."

A Polymarket spokesperson responded to Mansour by quoting a famous Emerson saying, "The louder he talked of his honor, the faster we counted our spoons." The spokesperson also mentioned that the platform has established a robust insider trading screening mechanism, reporting suspicious leads to law enforcement agencies nearly a hundred times and emphasizing, "We are committed to building a precise, fair, and transparent trading market."

As the prediction markets transition from niche races to mainstream popularity, both companies are facing increasing regulatory pressure. Attorneys General from multiple states have filed successive lawsuits against the two platforms, accusing their sports betting operations of violating regulations. Polymarket is also under investigation by the U.S. Commodity Futures Trading Commission (CFTC).

Kalshi's reports against Polymarket have become increasingly explicit. In May, former CFTC Commissioner and current Kalshi board member Brian Quintenz posted on Platform X, introducing Polymarket's user vetting mechanism and tagging the official account of the Southern District of New York Federal Prosecutor's Office.

The History of the Feud Between the Two Rivals

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

He soon encountered a formidable opponent. Mansour, who grew up in Lebanon and was a Castle Fund trader, co-founded Kalshi in 2018 with MIT alumna and current COO Luana Lopes Lara. Colleagues describe Mansour as sharp-minded and daring, with a somewhat reserved personality; Coplan is described as easy-going, art collector, music enthusiast, embodying 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. An insider recalled that in an awkward early meeting, Coplan mentioned that both had been raised by single mothers, a statement that made Mansour very uncomfortable.

But the two share a common belief: that the prediction market will reshape the finance and media industries, relying on "collective wisdom" to produce highly valuable information references. Both Polymarket and Kalshi betting platforms present bets in the form of "yes/no" questions, covering topics such as weather, Super Bowl events, and more. The overall amount wagered by users will determine the odds for the corresponding events.

Prior to launching its betting services in 2021, Kalshi had already applied for a full operating license from the CFTC. Three sources revealed that as early as the initial communication stage with regulatory authorities, Kalshi had raised compliance concerns regarding Polymarket.

The key liaison for Kalshi was 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, the regulatory agency fined Polymarket $1.4 million and ordered the platform to stop accepting bets from U.S. users.

This ban momentarily positioned Kalshi to dominate the U.S. domestic market. However, the company still needed to engage with regulators to seek more lenient operating rules. During the Biden administration, the CFTC banned election-related betting, leading Kalshi to sue the regulatory agency in 2023.

While Kalshi was embroiled in legal proceedings, and despite being prohibited from serving U.S. users, Polymarket continued to thrive. U.S. users only needed to use a Virtual Private Network (VPN) to modify their location and access the offshore website. Prior to the 2024 presidential election, the platform's odds sparked widespread discussions online, with its data showing Trump's victory probability significantly higher than traditional polls.

In June, Mansour bluntly stated as a podcast guest, "They completely bypassed the compliance process and launched the product directly, without any scruples."

On the eve of the election, Kalshi won in court, allowing licensed prediction markets to legally operate in the U.S. Polymarket still lacked domestic operating qualifications, but the platform's traffic surged, propelling Coplan to industry stardom.

In 2024, the New York Southern District Attorney's Office launched an investigation to verify whether Polymarket unlawfully provided services to U.S. users. A week after Trump's victory, the FBI raided Coplan's Manhattan apartment and confiscated all electronic devices.

Kalshi wasted no time in seizing the opportunity. A leaked chat screenshot from the Pirate Wires tech media revealed that Kalshi employee Keaton Inglis reached out to former NFL star Antonio Brown, instructing him to post on X platform accusing Coplan of being "guilty".

Antonio Brown, former NFL star

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

The search incident left Coplan and his team highly suspicious, and related rumors quickly spread through the media. Four sources with inside knowledge revealed that Polymarket internally speculated that Kalshi or its partners hired a private detective to track Coplan, and upon seeing the FBI visit, immediately leaked the information to the media.

Kalshi spokesperson Diana refuted, "This is completely unfounded, and the other party's imagination has reached an absurd level."

Undermining a Major Collaboration in Secret

In July of last year, Coplan went to the top-floor restaurant Manhatta in Manhattan for a crucial business dinner, with a 60-story panoramic view. He was dressed casually, carrying a bag of bagels.

The dinner's other party was billionaire Jeffrey Sprecher, founder of the Intercontinental Exchange. This $80 billion behemoth operates the New York Stock Exchange. The meeting of the new and old titans was also a key turning point in the competition between Polymarket and Kalshi.

Over the years, Kalshi had backing from A-list venture capital investors like Redpoint Ventures; Coplan had previously struggled to secure institutional funding. But both Coplan and Mansour were vying for investment from the Intercontinental Exchange, a giant looking to make a play in the prediction market arena.

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

Sources said Mansour was furious upon learning of the news. Five informants revealed that prior to the partnership announcement, Mansour and Kalshi investor a16z partner Alex Immerman separately met with the Intercontinental Exchange's executive team.

Several insiders provided conflicting accounts of the conversation, but three individuals confirmed that Mansour's communication with Immerman was primarily aimed at persuading Intercontinental Exchange to abandon this investment.

Kalshi spokesperson Diana stated that the company itself had "no intention to proceed with any collaboration with Sprecher."

Jeffrey Sprecher, Founder of Intercontinental Exchange

Ultimately, Sprecher chose to back Coplan and in October announced a potential investment of up to $20 billion in Polymarket. This was just one of the positive developments for Polymarket: in July last year, the Trump administration tightened enforcement measures, and the investigation against Coplan in Lower Manhattan was dropped. That same summer, 1789 Capital, a venture capital firm under the Trump family, also announced an investment in Polymarket.

Last year, Coplan stated on the "60 Minutes" program: "This administration strongly supports innovation and the crypto industry, especially backing Polymarket, which is very rare."

To take advantage of the policy tailwinds, Polymarket must obtain a US-based operational license. Coplan plans to acquire a company that already holds regulatory approval.

He once again ran into opposition from Kalshi. Five sources revealed that there were rumors in the industry that Coplan intended to acquire the niche prediction platform Railbird. Mansour promptly reported potential risks related to this acquisition target to senior CFTC officials.

Kalshi's report did not have the desired effect, and in June 2025, the CFTC approved Railbird's operational license. Coplan eventually spent $112 million to acquire another licensed entity, QCX. Despite restrictions on the offshore main platform, following the acquisition of QCX, Polymarket launched a US-based light version app, allowing them to reach a large number of American users.

Upon announcing the acquisition in July, Coplan posted an image of the American flag on social media with the caption: "We've been waiting for this day for too long. Polymarket officially returns to the US."

A Deliberate Provocation in the Business Game

Earlier this spring, the New York Knicks made it to the playoffs, and Mansour was seen at Madison Square Garden posting photos from the sidelines, dressed in the team's colors, with a big grin on his face.

Officially, this marks Kalshi's brand-new partnership celebration with the arena, with the sixth-floor corridor of the arena being officially named the Kalshi Corridor. However, industry observers see another layer of intention: a deliberate provocation.

Coplan, known before becoming famous for frequently sharing Knicks-related content on social media, was often seen courtside during regular-season games. Insiders revealed that before Kalshi finalized the partnership, Polymarket had also discussed a similar sponsorship but was unwilling to match the offer made by the former.

This also signifies that the industry rivalry, originally confined to the niche crypto circle, has now completely entered the mainstream view. In the first six months of this year, the total trading volume of both platforms exceeded $150 billion, a 1200% increase, undoubtedly intensifying the level of competition.

Based on current data, Mansour is currently in the lead. Following a new round of funding in May, Kalshi's valuation reached $22 billion, surpassing Polymarket by $7 billion. According to data from The Block, Kalshi's trading volume last month was $33 billion, twice that of Polymarket.

Diana denied that the collaboration with Madison Square Garden was aimed at Coplan: "We would not establish a business partnership to provoke our competitor; such claims are absurd."

The skyrocketing popularity of prediction markets has also brought about more stringent regulatory scrutiny, with most of the regulatory focus falling on Polymarket. In April of this year, a U.S. Special Forces soldier was indicted for using classified information to place bets on events related to the arrest of Venezuelan President Maduro through VPN access to the Polymarket offshore platform, illegally profiting over $400,000. A Polymarket spokesperson stated that the platform explicitly prohibits VPN access.

The two platforms have taken vastly different routes in controlling insider trading. Kalshi requires users to submit complete personal information before placing bets, and in some scenarios, even requires them to disclose their occupation; Polymarket has all transactions publicly recorded on-chain, making it easy for community users to check for any violations. U.S.-based app users must undergo real-name authentication, but users on the offshore main platform are not compelled to disclose private information such as their names or workplaces.

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

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

There has been frequent conflict between the two parties. According to sources familiar with the matter and documents reviewed by The New York Times, in the spring of 2025, several influencers under contract with Polymarket heavily promoted the news of the Kalshi and Elon Musk's xAI collaboration breaking apart.

That same year, Polymarket hired Uber early employee Max Crowley as VP of Partnerships. However, less than two months after joining, Crowley jumped ship to Kalshi, leaving Coplan extremely furious. Insiders say that during the transition, Coplan and the company's board lawyer Alex Spiro sent him a legal threat letter, but no legal action was ultimately taken.

Despite having shared industry interests, the two companies refused to collaborate. Kalshi formed an industry lobbying group to oppose restrictive prediction market regulations enacted by various states, uniting several competitors but expressly excluding Polymarket.

The following month, Kalshi suffered a setback in a state sports betting lawsuit, prompting Polymarket to promptly launch a new prediction market, allowing bets on the time of Kalshi's Massachusetts sports business shutdown.

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