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Bonus TL;DR
- Driven by a late-summer resurgence in sports trading, prediction markets posted a record-shattering $78.2 billion in notional volume in September, blowing past July’s previous high of $56.4 billion.
- The volume surge is driving massive institutional interest and sky-high valuations across the sector, with recent reports indicating Polymarket raised $1 billion at a $21 billion valuation, while Kalshi is reportedly in talks for a $1 billion raise at a staggering $40 billion valuation.
Prediction markets closed September at a record $78.2 billion in notional volume, surpassing July’s previous high of $56.4 billion as sports trading rebounded after a late-summer slowdown.
The new high matters because it shows how quickly event-based trading has scaled, with sports markets helping drive activity across major platforms including Polymarket, Kalshi, Polymarket US and Novig. The source data also points to rising institutional interest, with large fundraising rounds and acquisitions tied to the sector.
Weekly volume had slipped to about $10 billion from late July to mid-August before recovering in September. The latest weekly tally reached a cumulative $19.9 billion, according to the source report published by HackerNoon.
Sports markets helped power the rebound
Sports activity was a major piece of the September recovery. Between Sept. 14 and Sept. 20, soccer made up 46% of all sports volume on Polymarket, according to the report.
The NFL also stood out for ticket size. In that same period, 69% of NFL volume came from trades of $5,000 or more, a sign that larger bettors or trading firms were active in the market.
Across Kalshi, Polymarket, Polymarket US and Novig, match and game-winner markets traded $34.3 billion from June 29 to Sept. 30. The figures exclude spreads, totals, props, futures and parlays.
Within that total, Kalshi accounted for 67% of volume. By sport, tennis led with $9.17 billion, followed by MLB at $7.48 billion and the World Cup at $5.60 billion. WNBA and summer league games combined for $1.08 billion.
The source noted that the World Cup figure covers only part of the tournament, while Polymarket US sport-level data begins on July 23 and Novig data starts on Aug. 4.
Big-money deals show investor appetite
The volume surge came alongside a run of major corporate and fundraising developments.
On July 30, IG Group agreed to buy Underdog for up to $1.3 billion. On Sept. 1, reports said Polymarket raised about $1 billion at a $21 billion valuation in a round led by 1789 Capital.
At the end of the quarter, Kalshi was also reported to be in talks to raise about $1 billion at a $40 billion valuation, with Sequoia and Wellington leading. That would mark a sharp increase from Kalshi’s $22 billion valuation in a May round.
What comes next is whether September’s record holds through the fall sports calendar and whether the reported fundraising discussions, especially at Kalshi, result in completed deals on the terms that were reported.
Source: As reported by EdwinMunyui.
