Polymarket and Kalshi crossed a combined $150 billion lifetime volume milestone in April. This figure refers to combined historical trading volume across the two platforms (not April volume alone). The change in monthly activity appears to be a more useful April signal, though.
April Data Shows a Split
April saw $14.81 billion in notional trading volume on Kalshi, up 13.3% from the previous month. Polymarket moved the other way, with trading volume falling 14.8% from $10.57 billion in March to $9.01 billion in April. That widened Kalshi’s monthly notional lead over Polymarket to $5.8 billion.
User activity on Polymarket also softened. According to The Block, the number of active traders declined to roughly 643,000 in April from more than 733,000 in March. The decline came as the broader prediction market sector ended a seven-month streak of record monthly volume.
Sports Give Kalshi an Edge
Kalshi’s April growth appears tied to a more concentrated sports-led model. Sports and “Exotics” categories made up about 85% of total trading activity on Kalshi during the week of April 20. The platform also benefited from the NBA and NHL playoffs, the Masters, and the start of the MLB season.
On Polymarket, trading volumes are spread between sports, crypto, politics, finance, geopolitics, and culture markets. Such diversity gives the platform a wider topical reach, but it can also make volume more dependent on major news cycles and event-driven spikes.
It should also be noted that notional volume does not equal revenue, deposits, or customer losses. In particular, notional volume counts each contract based on its $1 maximum payout, rather than the price at which it was actually traded. Thus, it can be used for analysis purposes, but it does not indicate direct cash flow.
Growth Meets More Scrutiny
Prediction markets have been drawing increased attention politically and legally in the U.S. lately. In particular, the Senate has approved an immediate ban on senators, staff, and officers using prediction markets, citing concerns around sensitive information and event-based trading.
In addition, the CFTC has sued Wisconsin in response to the state’s lawsuits against prediction market platforms, including Kalshi, Polymarket, Crypto.com, Robinhood, and Coinbase. This case raises a larger issue of whether such products are to be viewed as federally regulated event markets or gambling activity under state jurisdiction.
Final Notes
April was not a simple slowdown story for prediction markets. This month proved that the sector remains huge, but growth is no longer moving evenly across the main platforms.
The sports-oriented nature of Kalshi is currently proving advantageous for its volume. Polymarket’s broader model, in turn, may need fresh catalysts to get back into its stride. The next test is whether both platforms can keep liquidity high amid regulatory pressure.
