Prediction market platform Kalshi has posted a record-high trading volume on explosive growth in sports markets, charting a growth path distinct from rival Polymarket.

Blockchain outlet Cryptopolitan reported on April 28 that Kalshi processed total trading volume of $3.4 billion over the past week, a 42-fold increase from a year earlier.

The growth came through a trading structure concentrated in specific categories, standing in clear contrast to Polymarket’s approach of maintaining a diversified portfolio. An analysis of trading data from the two platforms offers a detailed look at rapid shifts in the prediction market and factors behind sector-by-sector advantages.

Kalshi’s growth engine is sports, up 42-fold in a year.

In the last week of April ending April 26, Kalshi recorded weekly trading volume of $3.4 billion, setting an all-time high. A year earlier, weekly volume was about $80.5 million, meaning the market expanded by more than 42 times in just a year. Sports was the main driver. The sports category processed $3.0 billion, or 88 percent of total volume, and led the platform’s growth.

That figure is about $1.0 billion larger than Polymarket’s total weekly trading volume. Markets tied to the NBA playoffs are currently leading volume. Kalshi is attracting both professional bettors and retail traders with contract structures optimised for sports betting, including moneyline, spreads and futures. Over the same period, Kalshi’s crypto market recorded $334.1 million, while its political market totalled $16.8 million, less than 0.5 percent of the total.

Polymarket holds the line, with strength in politics and crypto.

Kalshi has taken the lead in overall trading volume by dominating sports, but Polymarket still maintains strong dominance in certain areas. Polymarket’s weekly trading volume was about $1.4 billion smaller than Kalshi’s, but its market distribution is far more balanced. Sports posted $959.1 million, while politics recorded $507.3 million and crypto about $416.0 million, with trading spread evenly across nine categories.

The gap between the two platforms was especially stark in the politics category. Polymarket’s political market volume is about 30 times larger than Kalshi’s. That suggests Polymarket, with a global user base, is capturing politically sensitive traders. Funds linked to the 2028 presidential election, geopolitical events and international elections continue to flow to Polymarket. While Kalshi pursues a sports-centred strategy, Polymarket has preserved a structural advantage in politics and macroeconomics, the core identity of prediction markets.

The platforms are strategically diverging, from competition to coexistence.

What the data shows in practical terms is that Kalshi and Polymarket are no longer competing for the same users. Kalshi is using the prediction market format to eat into the pie of existing regulated sports betting markets such as DraftKings and FanDuel. The fact that sports event contracts account for more than 85 percent of total revenue suggests Kalshi has effectively shifted into a sports-focused platform.

Polymarket, by contrast, has clearly established itself as a venue for global users looking to bet on elections, macro events and crypto outcomes. The two platforms are building separate ecosystems by setting different business models and target user bases. As Kalshi expands aggressively with sports betting as its weapon and Polymarket defends its position with politics and diversified indicators, the prediction market has entered a new phase.