Monthly trading volume on the Polymarket prediction market fell by about 8.9% in April, the first decline in month-to-month activity since August as rivals like Kalshi increased their market share.

Polymarket and its US-based trading application collectively generated more than $10.2 billion in volume in April, compared to more than $11.2 billion in March, according to data from Dune Analytics.

However, rival Kalshi’s April trading volume surged by about 13%, climbing to about $14.8 billion, Dune data shows.

The total monthly trading volume for prediction markets also increased to about $29.8 billion in April from about $26.5 billion in March, an increase of about 12.4%.

Polymarket’s volume drop came as the company attempts to fully integrate US markets again, amid increased legal and regulatory scrutiny of prediction markets by US lawmakers after the sector experienced a meteoric growth during the 2024 elections.