The week ending April 26 saw Kalshi processing $3.4 billion in trading volume according to data from Artemis. This marks a new all time high for the prediction market platform. The number that stands out however is not the total volume processed but rather the breakdown by category. Sports alone accounted for $3 billion or 88% of Kalshi’s entire weekly volume. This single category processed more volume than Polymarket’s total weekly volume by roughly $1 billion.
To put things into perspective on how fast Kalshi has grown, their weekly volumes sat at around $80.5 million a year ago. Today, this number has grown 42 times over.
Sports Is Kalshi’s Engine And the Gap Is Getting Wider
When looking at category-wise distribution, this tells you a lot about how the platform has positioned itself. Of the $3.4 billion, Sports markets recorded $3 billion in trading volume last week, which was a new all-time high in itself. Crypto markets came at a distant second at $334.1 million while the Politics category generated just $16.8 million, barely half a percent of total volume. The biggest event currently driving these volumes in the sports category are the NBA playoffs.
This is not an accident. Kalshi has built its growth around sports contracts, offering per-game moneylines, spreads, and futures across major leagues with contract structures that attract both sharp bettors and casual traders. The payoff is visible in the numbers. Sports event contracts accounted for over 85% of Kalshi’s weekly turnover, a figure that underscores how dramatically the sports category has grown relative to political and financial markets, a shift that has accelerated significantly over the past year.
Where Polymarket Still Holds Ground
Despite Polymarket recording roughly $1.4 billion less in trading volume in the week ending April 26, the volume distribution is in stark contrast to that of its biggest competitor. Total volume across the sports category stood at $959.1 million but politics saw $507.3 million and crypto generated around $416 million, both significantly larger volumes than in Kalshi. Spread across nine distinct categories, Polymarket’s volume is structurally more diversified.
On politics specifically, the gap is stark. Polymarket recorded $507.3 million in political market volume last week. Kalshi logged $16.8 million. That’s a roughly 30-to-1 disparity on the category that originally put prediction markets on the map. Polymarket’s global reach and its long-standing user base of politically engaged traders give it a structural advantage in that segment that Kalshi’s sports-first strategy hasn’t yet displaced. Markets around the 2028 presidential race, ongoing geopolitical events, and international elections continue to flow overwhelmingly toward Polymarket.
Two Platforms, Two Models
What these numbers actually reveal is that Kalshi and Polymarket are no longer really competing for the same user. Kalshi is eating into the regulated sports betting market, going after DraftKings and FanDuel territory with a prediction market wrapper. Polymarket is the venue for people who want to trade on elections, macro events, and crypto outcomes with a global counterparty pool.
