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Kalshi and Polymarket US set volume records before November midterms

Kalshi volume rose about 10 percent from September and Polymarket US rose about 15 percent, with open interest at 2.05 billion dollars on Kalshi and 384 million dollars on Polymarket US ahead of the November 3 midterms.

Kalshi and Polymarket US posted record monthly trading volumes in October, according to KuCoin. Kalshi reached about $65 billion, while Polymarket US reached $10 billion.

October activity increased on both platforms

Kalshi’s volume rose about 10 percent from September. Polymarket US recorded a larger percentage increase, with volume rising about 15 percent over the same period.

The figures place Kalshi ahead in reported monthly volume, even as Polymarket US grew faster month over month. Both platforms surpassed their previous monthly records, according to KuCoin.

Open interest ahead of November 3

Open interest stood at $2.05 billion on Kalshi and $384 million on Polymarket US ahead of the November 3 midterms. Those figures accompanied the volume update published on Nov 1, 2026, at 4:30 AM ET.

The supplied summary does not break out activity by contract or category. It therefore does not establish how much of October’s trading, or the reported open interest, was tied to the midterms.

What it means for prediction markets

  • Activity reached new highs: Both platforms recorded monthly volume records, with Kalshi reporting the larger total and Polymarket US the faster percentage growth.
  • Volume and open interest are distinct: The monthly trading totals should be read separately from the reported open-interest figures.
  • Election exposure remains unspecified: The timing puts the update ahead of the November 3 midterms, but the available figures do not isolate election-related positions or indicate an expected outcome.
KalshiPolymarketInfiniti MarketsInfiniti Signals

Sources & attribution

Published
  1. Source
    KuCoin
    Publisher
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    Source URL
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