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October trading and open interest reach fresh highs at Kalshi, Polymarket US

KuCoin reports, citing CoinDesk and The Block data, that Kalshi October volume rose about 10 percent from September's record and Polymarket US reached about 10 billion dollars, up about 15 percent. Open interest also hit records, with Kalshi at 2.05 billion dollars and Polymarket US at 384 million dollars.

Kalshi and Polymarket US recorded their highest monthly trading volumes in October, according to KuCoin, citing data from CoinDesk and The Block. Both platforms also reached records for open interest.

Trading activity exceeds September levels

Kalshi’s October volume reached about 65 billion dollars, roughly 10 percent above September’s record, according to KuCoin’s report published Oct 31, 2026, at 4:30 PM ET.

Polymarket US registered about 10 billion dollars in October trading volume, an increase of about 15 percent from September. Its percentage growth exceeded Kalshi’s, although Kalshi’s reported volume remained substantially larger.

Open interest also sets records

Open interest reached 2.05 billion dollars at Kalshi and 384 million dollars at Polymarket US, according to the same reporting. The record readings accompanied the monthly trading-volume highs at both platforms.

What it means for prediction markets

  • The reported figures show growth in both trading volume and open interest, rather than a volume record alone.
  • Kalshi led in absolute volume and open interest, while Polymarket US posted the larger percentage increase in monthly volume.
  • The summary provides no contract-level breakdown, so it does not establish which markets drove the gains or how broadly activity was distributed.
KalshiPolymarketInfiniti MarketsInfiniti Signals

Sources & attribution

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    KuCoin
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