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October prediction-market turnover hits record as political positions build

VIP-Grinders, in its October 2026 prediction markets report published November 4 using Artemis data, says open interest rose 41.5 percent to 3.13 billion dollars. Politics and elections took 4.5 percent of volume over the past year but held 41.2 percent of open interest, with political open interest rising 52 percent in October to 1.01 billion dollars.

Prediction markets recorded $121.28 billion in trading volume in October 2026, a record and an increase of 58.7%, according to VIP-Grinders. Kalshi and Polymarket together accounted for 97.7% of event contract volume.

The figures come from VIP-Grinders’ October 2026 prediction markets report, published November 4 using Artemis data. Open interest rose 41.5% to $3.13 billion, alongside the increase in trading activity.

Politics carries more weight in open positions

Politics and elections represented 4.5% of volume over the past year but accounted for 41.2% of open interest, according to VIP-Grinders. The figures highlight a substantial difference between the category’s share of trading activity and its share of outstanding positions.

Political open interest increased 52% in October to $1.01 billion. That growth exceeded the reported 41.5% increase in overall open interest, although the supplied summary does not specify the measurement window for the 41.2% share.

What it means for prediction markets

  • Platform concentration is high: Kalshi and Polymarket’s combined 97.7% share puts nearly all reported event contract volume on those two platforms.
  • Volume alone gives an incomplete picture: Politics and elections had a relatively small share of annual turnover but a much larger share of open interest.
  • The figures measure activity, not direction: Rising volume and open interest do not, on their own, indicate which political outcomes traders consider more likely.
KalshiPolymarketInfiniti MarketsInfiniti Signals

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    VIP-Grinders
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