An industry commercial war that breaks the bottom line.

Written by: David Yaffe-Bellany, William K. Rashbaum, The New York Times

Translated by: Luffy, Foresight News

On a morning in November 2024, Polymarket founder Shayne Coplan woke up to uninvited guests in his home. Several FBI agents broke into his apartment in New York with a battering ram, searching for evidence related to illegal gambling on the platform.

Coplan spoke out on social media, claiming that the search was politically motivated suppression initiated by the Biden administration. However, privately, he and his team of advisors had other suspects in mind, attributing the troubles Polymarket faced to their biggest competitor—the CEO of the prediction market platform Kalshi, Tarek Mansour.

Four insiders revealed that months before the FBI's visit, Kalshi’s lawyers had gone to the Manhattan U.S. Attorney’s Office to report issues regarding Polymarket, a fact that had never been disclosed publicly before. Insiders said the lawyers detailed Polymarket's operational model to prosecutors and pointed out a key issue: the platform, which should be prohibited for domestic U.S. use, remained accessible to users.

This confrontation was just an extreme conflict arising from the long-standing grievances between Kalshi and Polymarket. Both are currently among the hottest startups in the tech industry. The clash of ambitions among Silicon Valley founders is nothing new; industry rivalries fueled by ego are everywhere, just like Uber's competition with Lyft in the ride-sharing market; the public feud between OpenAI's Sam Altman and Anthropic's Dario Amodei also became a captivating subplot in the AI industry.

But the rivalry between the 28-year-old Coplan and the 30-year-old Mansour has long surpassed the boundaries of normal business competition. More than forty industry insiders interviewed anonymously said the two, both newly minted billionaires, are intent on monopolizing the prediction betting market covering categories like sports, politics, and entertainment, and they harbor extreme animosity towards each other, with this antagonistic sentiment permeating nearly all business interactions between the two companies.

Shayne Coplan, Polymarket Founder

Dustin Gouker, who has long written columns on the prediction market industry, stated, "The animosity between the two has run too deep; the conflict is already mixed with personal grievances."

This feud has spread to internal company meetings, U.S. Congressional hearings, influencing regulatory policies in Washington, and triggering unprecedented industry attention and regulatory concerns. The two companies have repeatedly filed trademark applications against each other, competed for the same business deals, poached each other's talent, publicly accused one another in the media, and directly attacked each other on social platforms. Both have established business collaborations with Donald Trump Jr., which is a common public relations strategy within the Washington circle during Trump's administration.

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

The hostility between the two is not merely a battle for market share but includes deeper discrepancies regarding ethical boundaries and business morality. Kalshi presents itself as a compliance benchmark, insisting on obtaining U.S. regulatory approval before launching domestic operations, while Polymarket operates offshore and has not obtained a domestic license. Kalshi strictly enforces real-name registration rules and blocks sensitive betting categories; Polymarket allows users to register without submitting personal information and even enables betting on events like the timing of missile strikes in Israel.

Although Coplan and Mansour have encountered each other over the years, they now have virtually no contact and only engage in mutual disparagement from a distance. Mansour, a graduate of MIT and a self-proclaimed math enthusiast, compared their competition to the legendary rivalry between Tom Brady and Eli Manning, suggesting a healthy competition. But recently, he directly criticized Polymarket's operational model as "illegal and unethical," pointing out that its offshore platform is operated by a Panama entity.

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

Coplan dropped out of New York University and is adept at promotion, rarely mentioning Kalshi in public. However, two insiders revealed that he privately claims Kalshi has merely copied Polymarket’s model and believes Mansour has been looking for ways to suppress him. Coplan firmly believes that his platform is the best solution in the industry, stating on CBS's "60 Minutes" last year, "This is the most precise information tool humanity currently possesses."

Kalshi spokesperson Elisabeth Diana stated that the company learned about the FBI search through news reports. She added that Kalshi regularly communicates with regulators on compliance issues and has publicly pointed out, "There are companies that harm user rights and damage industry reputation."

Tarek Mansour, Kalshi Co-founder

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

Polymarket’s spokesperson quoted Emerson in response to Mansour: "Those who boast of their own character must first take care of their own silver spoons." They also stated that the platform has established a comprehensive insider trading screening mechanism, reporting suspicious leads to law enforcement nearly a hundred times, and emphasized, "We are committed to creating a precise, fair, and transparent trading market."

As prediction markets transition from niche tracks to widespread popularity, the regulatory pressure faced by both companies continues to rise. Attorneys General from multiple states across the U.S. have filed lawsuits against both platforms for violating gambling regulations in their sports betting businesses; Polymarket is also under investigation by the Commodity Futures Trading Commission (CFTC).

Kalshi's complaints against Polymarket have become increasingly straightforward. In May, former CFTC Commissioner and current Kalshi director Brian Quintenz posted on X, introducing 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 Origins 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 Lower Manhattan, converting a bathroom into an office, with just a laptop as all his equipment. At that time, he considered himself a newcomer to the industry, developing a completely non-mainstream new product.

He soon encountered a formidable competitor. Mansour grew up in Lebanon and was once a trader at Castleton Partners; in 2018, he co-founded Kalshi with his MIT classmate, current COO Luana Lopes Lara. Colleagues describe Mansour as bright and daring, with a somewhat reserved personality; Coplan, on the other hand, is affable, collects art, loves music, and carries the relaxed demeanor of a New Yorker.

Luana Lopes Lara, Kalshi Co-founder

The relationship between the two has never been particularly friendly. Insiders recall an awkward encounter years ago where Coplan mentioned that they both had been raised by single mothers, which made Mansour quite uncomfortable.

However, they share a common belief: prediction markets will reshape the finance and media industries by producing highly valuable information references through "collective intelligence." Both Polymarket and Kalshi present bets in the form of "Yes/No" questions, covering betting subjects such as weather, Super Bowl events, etc. The total amount wagered by users determines the odds for the corresponding events.

Kalshi applied for a complete business license from the CFTC even before launching its betting business in 2021. Three insiders revealed that during early communications with regulators, Kalshi had already reported compliance issues concerning Polymarket.

The main contact for this 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 within the U.S. without permission. In January 2022, regulators fined Polymarket $1.4 million and ordered the platform to stop accepting bets from U.S. users.

This ban temporarily led Kalshi to hope for a monopoly in 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 in 2023, Kalshi sued the regulatory agency.

While Kalshi was embroiled in legal disputes, Polymarket continued to thrive, even despite not being able to serve U.S. users. American users could still access the offshore site using VPNs to modify their locations. Before the 2024 presidential election, the platform's odds generated significant online discussion, showing that the probability of Trump winning was much higher than traditional polling indicated.

During a podcast in June, Mansour stated, "They completely bypassed the compliance process and launched the product without any concerns."

On the eve of the election, Kalshi won a court victory, allowing licensed prediction markets to legally operate in the U.S. Polymarket still lacked domestic operating qualifications, but its traffic soared, and Coplan became a prominent figure in the industry.

In 2024, the U.S. Attorney's Office for the Southern District initiated an investigation to verify whether Polymarket had violated regulations by opening services to U.S. users. One week after Trump’s victory, the FBI raided Coplan’s Manhattan apartment, seizing all electronic devices.

Kalshi immediately seized the opportunity to create momentum. The 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 claiming that Coplan was "guilty."

Antonio Brown, former NFL star

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

The search incident left Coplan and his team with many suspicions, and related rumors quickly spread through the media. Four insiders revealed that Polymarket’s internal speculation suggested that Kalshi or its partners hired private investigators to follow Coplan and tipped off the media immediately after the FBI arrived.

Kalshi spokesperson Diana denied this, stating, "This is completely nonsense; the other side's imaginations have become absurd."

Subtly Disrupting Major Collaborations

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

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

For years, Kalshi has had high-profile investors like Sequoia Capital; Coplan had repeatedly hit walls trying to connect with large institutional funding. Yet both Coplan and Mansour were vying for investment from the Intercontinental Exchange, which had intentions of entering the prediction market space.

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

Insiders said that Mansour was extremely angry upon learning of the news. Five insiders disclosed that before the cooperative announcement, Mansour spoke individually with a16z partner Alex Immerman, who was an investor in Kalshi, urging the board at the Intercontinental Exchange to abandon the investment.

Several insiders provided varied accounts of the conversation details, but three confirmed that Mansour’s communication with Immerman was essentially an attempt to dissuade the Intercontinental Exchange from making the investment by any means necessary.

Kalshi spokesperson Diana stated that the company had "no intention of advancing collaboration with Sprecher."

Jeffrey Sprecher, founder of Intercontinental Exchange

In the end, Sprecher chose to bet on Coplan, announcing a maximum $2 billion investment in Polymarket in October. This was just one of the string of good news Polymarket received: in July last year, the Trump administration tightened enforcement against regulations, and the Southern District of New York closed the investigation against Coplan; also that summer, Donald Trump Jr.'s venture capital firm, 1789 Capital, announced its investment in Polymarket.

Last year, Coplan stated on CBS’s "60 Minutes", "This administration is strongly supporting innovation and the crypto industry, especially Polymarket, which is quite rare."

To seize policy advantages, Polymarket needed to obtain a domestic operating license in the U.S. Coplan planned to acquire a company that already had compliance qualifications.

He once again faced obstacles from Kalshi. Five insiders revealed that there were rumors that Coplan intended to acquire the niche prediction platform Railbird, and Mansour immediately reported the risks associated with that acquisition to senior CFTC officials.

Kalshi's reports were 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 App for the U.S. market, enabling access to a massive base of domestic users.

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

Deliberately Provocative Business Games

This spring, as the New York Knicks reached the playoffs, Mansour posted photos of himself watching the games at Madison Square Garden, dressed in the team colors, smiling broadly.

Officially, this was a celebration of Kalshi's new partnership with the venue, with the sixth-floor corridor of the arena formally renamed as the Kalshi Corridor. However, industry observers noted another underlying intention: a deliberate provocation.

Before Coplan rose to fame, he often shared Knicks-related content on social media and had appeared numerous times at the arena during regular season games. Insiders revealed that before finalizing the partnership, Polymarket had also negotiated for similar sponsorship but refused to match the offer made by Kalshi.

This also marked a shift, as the industry feud, which had been limited to the niche crypto circle, completely moved into the public eye. In the first six months of this year, the total transaction volume between the two platforms surpassed $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 firm 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 intended to target Coplan: "We would never finalize a business collaboration for the sake of provoking a rival; that statement is utterly ridiculous."

The surge in interest in prediction markets has also attracted more stringent regulatory scrutiny, with much of the focus falling on Polymarket. In April this year, a U.S. Army Special Forces soldier was charged for using classified information to log into Polymarket’s offshore platform via VPN to bet on the event of Venezuela's President Maduro being arrested, illegally profiting over $400,000. A Polymarket spokesperson stated that the platform strictly prohibits VPN access.

The two platforms have fundamentally different approaches to managing insider trading. Kalshi requires users to submit complete personal information before placing bets, while Polymarket maintains a fully transparent transaction chain, allowing community users to self-check for any violations. While users on the U.S. domestic app must verify their identity, the offshore main platform still does not require users to disclose personal information such as their name and workplace.

Polymarket’s paid collaborator Aj Pleasanton commented that this model is quite common in the crypto industry, with users generally preferring to operate anonymously.

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

Conflicts between the two occur frequently. According to documents reviewed by insiders and The New York Times, in spring 2025, multiple influencers contracted with Polymarket spread rumors about the breakdown of cooperation between Kalshi and xAI, a company owned by Elon Musk.

In the same year, Polymarket hired early Uber employee Max Crowley as Vice President of Partnerships, but less than two months after joining, Crowley transitioned to Kalshi, which greatly angered Coplan. Insiders stated that during the transition period, Coplan, along with the company board's attorney Alex Spiro, sent a letter threatening to sue him, though no lawsuit was ultimately filed.

Even with shared industry interests, the two companies absolutely refuse to cooperate. Kalshi has formed an industry lobbying group to combat restrictive regulations on prediction markets being enacted by various states, collaborating with multiple peers while excluding Polymarket.

The following month, after suffering a setback in a sports betting lawsuit in one state, Polymarket immediately launched a new betting item, opening betting on how long it would take for Kalshi to suspend its Massachusetts sports operations.