Prediction markets closed September with $78.2 billion in notional volume, marking the largest month ever compared to July’s record which sat at $56.4 billion.
We’re putting together our Q3 report, and this week’s letter draws on three fundamental charts that we’ve observed so far.
Weekly Volume Has Doubled from the Summer Lull
The summer was relatively calmer for prediction markets, with contract volume sliding as the World Cup wound down; volumes settled near $10 billion a week from late July to mid-August.
Looking at this chart, September has been a recovery month; the latest weekly volume shows a cumulative of $19.9 billion.
A good chunk of this has been sports driven, with soccer league games and the NFL getting a good amount of traction. Between Sept. 14-20, soccer accounted for 46% of all the sports volume on Polymarket, while the NFL was the largest ticket market; 69% of its volume came from $5,000-plus tickets.
Billion-Dollar Deals and a Wider Partner Network
Institutional capital flows are another trend showing that prediction markets are getting ready for Wall Street faster than most expected.
Three transactions of about $1B or more were announced or reported in Q3. IG Group agreed on July 30 to buy Underdog for up to $1.3B, and Polymarket raised about $1B at a $21B valuation in a round led by 1789 Capital that was reported on Sept. 1.
At the end of the quarter Kalshi was in talks to raise about $1B at $40B, with Sequoia and Wellington leading. Its round in May valued it at $22B. Early-stage notable rounds were Pascal, River Markets and Adjacent.
Tennis Led a Changing Sports Calendar
The weekly lead in winner-market volume passed from the World Cup to MLB, then to tennis for five weeks, before NFL and college football took over in September’s full weeks.
Across Kalshi, Polymarket, Polymarket US and Novig, match and game-winner markets traded $34.3 billion from June 29 to September 30, with Kalshi accounting for 67% of that total.
Tennis was the largest sport over the period at $9.17 billion, ahead of MLB at $7.48 billion and the World Cup at $5.60 billion. With the NBA out of season, WNBA and summer league games traded $1.08 billion.
Baseball and tennis carried much of the activity between the World Cup’s final stages and football’s September return.
It’s also worth noting these are winner markets only, excluding spreads, totals, props, futures and parlays. The World Cup figure covers only part of the tournament and excludes Polymarket US, whose sport-level data starts on July 23. Novig’s data begins on August 4.
We’ve also launched a dedicated intelligence letter for a closer weekly look at the trading behind the games, you can subscribe to Prediction Frontier Sports.
