Prediction market volume hits $120.7 billion in October, up 64%
Prediction market trading volume reached $120.7 billion in October, a 64% increase from September, according to DeFi Rate's volume tracker. Kalshi recorded $98.2 billion in monthly volume, its busiest month on record, and crossed $5 billion in a single day for the first time. Polymarket US reached $14.8 billion. Underdog and Novig each more than doubled their monthly totals as combo trading expanded across exchanges.
Kalshi's $98 billion month proves its retail infrastructure can handle CFTC-regulated volume at derivatives-exchange scale. The $5 billion single-day print and record open interest show liquidity depth that rivals traditional futures venues. That matters because Kalshi is now pitching institutional desks through its Tradeweb and BMLL partnerships, and those gatekeepers require volume proof before adding a new asset class.
Underdog and Novig doubling suggests the combo-trading format is pulling users from sportsbooks into event contracts, expanding the total addressable market rather than just shifting existing traders. The risk is concentration: Kalshi's 81% share of the $120.7 billion total leaves the sector vulnerable to any operational or regulatory disruption at one venue. Rivals must prove they can scale independently before institutions commit to multi-platform strategies.
Joins a three-day run of major Kalshi milestones alongside its $1 billion raise at a $40 billion valuation and its Tradeweb-BMLL institutional push, cementing the platform's position as the volume leader regulators and competitors must now measure against.