How World Cup Prediction Markets Fared: Data for Kalshi, Others

Kalshi bills itself as the “trade on everything” exchange. During the World Cup, it doubled as the advertise on everything exchange. Lionel Messi and his Argentina teammates glaring down from a Times Square billboard alongside a Kalshi logo. Timothée Chalamet at the dentist, repeating “Kalshi, Kalshi, Kalshi” in a national TV ad campaign. Pitch-side signage at the World Cup final bearing company’s name. Led by Kalshi and Polymarket, prediction market exchanges approached the grandeur of the World Cup as a golden opportunity to convert sports fans into new customers. The industry spent hundreds of millions of dollars on World Cup advertising and sign-up bonuses. Top-line growth followed: It only took a dozen or so days in July for U.S. prediction markets to reach the total notional volume the entire industry hit in May (a shade over $20 billion). As operators gobbled up users nationwide, the market share rankings hardly changed, according to notional volume data compiled from public Dune dashboards and via independent Sportico research. Kalshi conceded little ground during the World Cup, while Polymarket maintained second place among federally regulated exchanges. The biggest development has arguably been Robinhood’s newly activated exchange surpassing Crypto.com for third place in notional volume. This occurred despite Crypto.com’s exchange receiving more of a volume boost than Robinhood from prominent third-party brokers, such as Underdog Fantasy and Fanatics. Notional volume is an imperfect measurement of exchange vitality because it lumps in participation from institutional funds and affiliated trading arms rather than just retail users. The metric deviates further from a true representation of how much new user risk is entering the market when single contracts are bought and sold multiple times. Long-shot retail bets such as parlays also juice the numbers. Sportico‘s analysis uses notional volume because it’s still the best data point all exchanges publicly report on a regular basis. Leaders keep leading Ahead of the World Cup’s final weekend, Kalshi had spent an estimated $32 million on national linear TV advertising this year, according to iSpot data provided to Sportico. That was just the price of appearing on air and didn’t include what Kalshi paid in-demand stars like Chalamet to act in its promos. The 36 ads Kalshi showed during live World Cup matches on Fox and Telemundo broadcasts through the semifinals accounted for about 40% of Kalshi’s 2026 national TV spending. Polymarket aired 45 ads during live World Cup matches during that timeframe. The rest of the U.S. betting industry combined for just 22, per iSpot. Additionally, Kalshi and Polymarket shelled out many more millions on radio, physical activations like the Times Square billboards, paid partnerships with media companies to share betting referral links and tie-ups with popular social media influencers. Kalshi declined to say exactly how much it spent on the World Cup. Polymarket did not respond to a request for comment on its expenses. The advertising efforts seemed to pay off. Through Sunday’s World Cup final, Kalshi accounted for roughly 83% of notional trading volume out of CFTC-approved prediction market exchanges this month—the same as the company fared in June. Kalshi, which recorded an 88% share in May, has yet to experience a month below 80% U.S. notional volume share among regulated entities in its feverish two-year run from a sub-$1 billion valuation to a valuation above $20 billion. Polymarket’s U.S. exchange (a separate product from its international prediction market) also held firm through the World Cup, rising to about 10% of U.S. prediction market notional volume share in June and July after sitting at roughly 8.5% in May. This analysis does not include Polymarket’s offshore exchange, which is not regulated by the CFTC nor available to U.S. bettors (at least in theory). While regulatory worries loom—and litigation over whether any prediction markets should be allowed at all under federal oversight continues—Polymarket U.S. establishing market share is a welcome sign for investors after the company’s product team fumbled in its attempt to be fully operational during the 2025 NFL season. Polymarket didn’t move its U.S. app out of beta until March. Polymarket U.S. expects to fully roll out custom parlays this month, a development that should help it close some of the gap with Kalshi in notional volume. Parlays inflate the industry standard notional volume metric, meaning that without combo bets in recent months, Polymarket has been at an accounting disadvantage. Third-place match Behind Polymarket U.S., only Robinhood-owned Rothera (4.6%) and Crypto.com-owned Nadex (2.4%) break the 1% mark in share of notional volume this month. Sportico’s market share calculation reflects the exchanges that execute trades, not brokers that do not own the underlying exchange infrastructure or that have not yet activated exchanges they recently acquired. DraftKings, Fanatics, FanDuel, Underdog Fantasy and PrizePicks all routed at least some of the bets placed in their apps through exchanges they don’t own. DraftKings’ DKeX exchange, rebranded from Railbird, has a notional volume market share of about 0.01% in July, though volume is ticking upward. CME Group, which executes some FanDuel Predicts wagers through a joint venture, is at about 0.02%. DraftKings and FanDuel broker bets through multiple exchanges. DraftKings expects to increasingly lean on DKeX as the year progresses, and Underdog has said its Aristotle exchange will be fully operational by NFL season. The established gaming firms also offer betting in different forms, such as state-regulated traditional sportsbooks, online casino and daily fantasy sports that generate revenue while they roll out their prediction markets. And some of them are only facilitating sports prediction market wagers in places where they don’t have state gaming licenses, so as to not antagonize those regulators. “Still very early as we ramp into this,” a DraftKings spokesperson told Sportico. FanDuel declined to comment. As Sportico has reported, many companies prefer to own an exchange, instead of just being a broker, making the initial costs to acquire or build them worthwhile. Owning an exchange can require a $100 million-plus upfront investment but gives an operator full control over creating new types of bets and is responsible for resolving wagers. The operator can also usually make more revenue on fees per-wager than they would as a broker, which charges small fees on top of what the underlying exchange collects. Rothera, the exchange Robinhood purchased last fall and relaunched with Susquehanna International Group this year, doesn’t rely on significant order flow from independent brokers. By contrast, Crypto.com’s numbers are pumped up by myriad third-party partners, many of whom plan to abandon its Nadex exchange once they get their own exchanges fully operational. It is possible, though, for Crypto.com to onboard new broker partners to make up for those losses. There is not publicly available data for the exact percent of Nadex volume coming from brokers independent of its parent company, Crypto.com. But a Bank of America analyst report from June claims Nadex’s independent brokers are responsible for most of its traffic. Crypto.com declined to comment. Robinhood gained market share during the World Cup even though it did not partake in the TV advertising blitz. And while Robinhood promoted prediction markets on Google and Meta platforms through its own brand accounts, the company did not appear to pay additional money to affiliated creators, transparency records show. It spent $107 million on marketing in the first quarter of this year, per SEC filings, but that money was spread out promoting all of its financial products. Publicly traded companies FanDuel parent Flutter Entertainment and DraftKings both spent about four times the amount Robinhood did in the U.S. in their most recently reported quarters. Robinhood declined to comment. ‘Grow or die’ Kalshi and Polymarket’s World Cup advertising gave them a presence at the biggest event in sports like no one else in their industry. The efforts appeared to successfully drive customer acquisition. But even if the flood-the-zone tactic worked, it’s attracted naysayers, too. Coming out of the World Cup, multiple Kalshi and Polymarket competitors told Sportico they are hoping to seize on recent public controversies of the incumbents, both before and during the soccer tournament, that stem from marketing styles they say prioritize virality over honest engagement. For example, Kalshi and Polymarket have faced backlash for affiliated influencers hawking their apps without ad disclosures, and for, in the eyes of critics, overselling the chances of retail users succeeding with their bets. The firms insist their product is more of a financial asset class than a form of gambling. There are signs regulators could look to rein in their approaches—Polymarket is reportedly under federal investigation over its alleged misleading advertisements, and the Better Business Bureau has asked the government to look into Kalshi’s use of undisclosed social media ads. “Sort of calling it like it is, I think there’s a lot of BS, frankly, that goes on in the industry, [people] not necessarily being the most forthright,” Jacob Fortinsky, CEO of sports-focused prediction market Novig, told Sportico. A Kalshi spokesperson said the company is forthright with its customers and that it’s developed and distributed guidelines for affiliates. Polymarket did not respond to a request for comment, but last month it said it was auditing its promotional content policies. Startups face pressure to stand out with outlandish or emotionally appealing digital content, Brando Babini, founder of the soccer startup Youth 4 Youth FC, told Sportico in a video interview. “You grow or die,” he said. Babini built an audience from scratch through engaging social media videos posted on TikTok and Instagram; those accounts have reached almost 60,000 followers across the two platforms with a small staff, and he’s parlayed that reach into a corporate partnership with Nike. Kalshi and Polymarket, of course, are approaching social media at a greater scale—and with loftier investor expectations—having rocketed to over 5 million combined followers between their primary X, Instagram and TikTok accounts. “With short-form content, you need like 40 things happening in a six-second video, you know, like me screaming, another kid in the background losing it,” Babini said. “Every little factor has to be right.” During the World Cup, Kalshi and Polymarket benefitted from another trick: Affiliates suggesting winnings are just around the corner. In a Kalshi-sponsored TikTok video on July 5 from social media influencer @actuallyjose, the content creator with 380,000 followers, dons a Mexico national team kit and raises his voice as he plays up his fandom ahead of Mexico’s World Cup match against England. “Is this a lock, guys?” @actuallyjose asks. “I think it is. Mexico’s got it in the bag.” Kalshi rose to new heights with England’s win over Mexico that night, recording the highest betting volume on a single sports result in prediction market history at $223 million on which team would advance. The whiplashing momentum of the 3-2 match inspired robust in-game betting activity. The event was by some measures also one of the worst results for retail users in prediction market history. This weekend, Kalshi’s World Cup winner market scored about $166 million in notional volume from the World Cup semifinals through the final whistle. Separate markets related to Spain’s title-winning match, such as the spread, prop bets on goalscorers and custom parlays, garnered additional tens of millions in notional volume. It won’t be long before the next major battleground for prediction markets comes into focus. The NFL regular season starts in 50 days. With reporting contributions from Anthony Crupi.