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Kalshi volume lead underscores Polymarket’s shrinking share of prediction trading

CryptoBriefing reported Polymarket's share fell from 96 percent two years ago to 27 percent, with Kalshi holding about 83 percent of volume among United States regulated platforms in October. Kalshi carried about 2.05 billion dollars in open interest against about 384 million dollars at Polymarket US.

Polymarket’s share of prediction-market trading has fallen to 27 percent from 96 percent two years ago, according to CryptoBriefing. Kalshi now handles nearly three times Polymarket’s trading volume.

Volume and open interest favor Kalshi

CryptoBriefing reported that Kalshi accounted for about 83 percent of volume among United States regulated platforms in October. That figure describes a narrower market than the reported overall share for Polymarket.

The open-interest comparison also showed a substantial gap. Kalshi carried about 2.05 billion dollars in open interest, compared with about 384 million dollars at Polymarket US, according to CryptoBriefing.

Keeping the comparisons distinct

The report, published Oct 31, 2026 at 6:00 PM ET, presents several measures of competitive position. Trading volume measures activity, while open interest captures outstanding positions; the figures should not be treated as interchangeable.

The distinction between Polymarket and Polymarket US also matters. The 27 percent trading-share figure refers to Polymarket, while the 384 million dollar open-interest figure specifically concerns Polymarket US.

What it means for prediction markets

  • Kalshi’s volume lead indicates that trading activity has shifted substantially from the distribution reported two years ago.
  • Its roughly 83 percent share applies to United States regulated platforms in October, not necessarily to the same universe underlying Polymarket’s 27 percent share.
  • The open-interest gap offers a separate measure of platform scale, but these aggregate figures do not establish liquidity or pricing quality for any individual contract.
KalshiPolymarketInfiniti MarketsInfiniti Signals

Sources & attribution

Published
  1. Source
    CryptoBriefingcryptobriefing.com
    Publisher
    https://cryptobriefing.com
    Source URL
    The feed did not publish this story's article address.

Full attribution under the Digital Millennium Copyright Act (DMCA), 17 U.S.C. § 512: this article is an original report by Infiniti Intelligence that summarizes the reporting of the publishers named above, links to their original work, and reproduces no protected expression beyond brief factual reference and in-line attribution (“according to CryptoBriefing”). All rights in the underlying reporting remain with the publishers listed; nothing here implies endorsement by or affiliation with them. Rights holders may request correction, update or removal through the contact address published at infiniti.w3ai.io.

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