Kalshi’s United States web traffic has exploded more than 1,500 percent in under a year, reaching 15.4 million visits in July from just under one million in August 2025, according to Similarweb estimates, a surge that arrives precisely as courts and state regulators intensify their scrutiny of the prediction market platform’s expanding event-contract business.
The numbers reviewed Friday tell a story of extraordinary concentration and growth. US traffic accounted for nearly 80 percent of Kalshi’s total visits in July, up from 72.8 percent in August 2025, showing that the platform’s expansion has remained overwhelmingly American even as international curiosity grows. The timing is awkward for the company: New Jersey is taking its dispute over Kalshi’s sports contracts to the US Supreme Court, and Michigan continues its aggressive campaign to block the platform’s operations, making the traffic boom both a measure of product-market fit and Exhibit A for regulators arguing the stakes are now systemic.
Volume growth dwarfs the traffic story
If the visitor numbers are striking, the trading figures are staggering. Kalshi recorded approximately 40 billion USD in monthly notional trading volume in August, up from 874 million USD a year earlier, an increase of roughly 4,500 percent according to a Dune Analytics prediction market dashboard. That growth outpaced traffic by a factor of three, meaning the average user is not just visiting but trading far more intensively.
Across the entire prediction market industry, monthly notional volume rose to 50.7 billion USD from about 2 billion USD over the same period. Kalshi alone accounts for nearly 79 percent of that total, a market share that would trigger antitrust conversations in any mature industry. Polymarket, the sector’s other heavyweight, is fighting for the remainder alongside a long tail of newer entrants.
Sports contracts are the engine. They accounted for 83 percent of Kalshi’s trading volume in July, Barron’s reported, a concentration that explains why state gaming regulators have moved from curiosity to open hostility. The company’s transformation from a niche CFTC-regulated events exchange into what increasingly resembles the largest sportsbook in America by notional volume is exactly the trajectory that New Jersey and Michigan say Congress never authorized.
Traffic from restricted jurisdictions raises compliance questions
The Similarweb data also contains a quieter controversy. Canada generated about 450,000 visits to Kalshi’s website in July, up from roughly 50,000 a year earlier, while UK traffic increased to 296,000 from 31,000. Both countries are among the jurisdictions where Kalshi’s own member agreement prohibits users from directly accessing or trading on the platform.
The shares slipped as total traffic ballooned, with Canada falling to 2.3 percent from 3.8 percent and the UK to 1.5 percent from 2.4 percent, but the absolute numbers grew ninefold. Kalshi has taken a partnership route in Canada, teaming with financial services company Wealthsimple in June to provide access to nearly 4,000 eligible contracts through a separate app. Cointelegraph contacted Kalshi for comment on the traffic from restricted jurisdictions but had not received a response by publication.
Website visits are not trades, and curiosity traffic from blocked jurisdictions is not itself a violation. But at a moment when Kalshi’s legal fate may be decided by whether its activity constitutes regulated events contracts or illegal sports wagering, data showing hundreds of thousands of monthly visits from places it cannot legally serve gives plaintiffs an easy narrative.
The setup for a Supreme Court autumn
The growth data frames the legal endgame now underway. A platform doing 40 billion USD in monthly volume, four-fifths of it in sports, with 80 percent of its audience in the US and a Supreme Court petition pending, is no longer a fintech curiosity. It is a systemic market whose classification will determine the regulatory perimeter for the entire prediction market sector.
For traders, the practical takeaway is concentration risk. Nearly four-fifths of industry volume flows through one venue whose core product line faces an adverse ruling risk. A decision against Kalshi’s sports contracts would not merely dent one company; it would reprice the entire prediction market complex overnight, with Polymarket and offshore venues positioned to absorb displaced flow.
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15.4 million visits in july and climbing straight into a supreme court fight. you love to see product market fit and a legal death race on the same chart
exactly, michigan spending years trying to block them while us traffic does a 15x is the most telling metric in the whole piece
the volume number is the wild part. 874 million to 40 billion notional in twelve months, thats not adoption thats a casino finding its floor
nj taking sports contracts all the way to scotus while kalshi prints. would love a breakdown of how much of that 40b is sports vs election money
would guess sports dominates the 40b. nj would not be burning years of scotus litigation over election contracts alone
Election night cleared enormous volume for them last cycle. Sports is the legal fight, but do not sleep on election money, that was the market that built Kalshi in the first place.
notional undersells it, kalshi also runs the clearing and books the spread as the house. 40 billion through your own books is real money
15.4 million US visits while new jersey drags it to the supreme court. regulators built their own systemic risk argument for them, 40 billion monthly volume is not a niche product
The Similarweb figure is web traffic only, app numbers are probably higher. Michigan trying to block operations while 80% of visits are American tells you the state patchwork is already failing.
App numbers being higher tracks, everyone I know trades kalshi from the phone. Web visits undersell it badly.
everyone hyping the 40 billion forgets kalshi makes almost nothing per contract. notional is impressive, revenue is a rounding error next to the legal bills
fees per contract are tiny but kalshi also runs the clearing. spread plus membership across 40 billion notional is not a rounding error anymore
and they own the order book data on top of clearing. every leg of the trade monetized while nj argues about definitions, vertical integration beat the regulators to it
874M to 40B monthly in twelve months. michigan trying to block them at this point is just yelling at a waterfall lol
similarweb misses api and bot traffic too. whatever scotus rules on the nj sports case, the volume already made this impossible to regulate as a niche
nj’s whole scotus argument is that the sports contracts violate state gambling law though. even 40 billion monthly notional does not change what the contract actually is, the volume cuts both ways