Prediction markets posted their strongest month on record in October, with total monthly trading volume surpassing $100 billion for the first time and reaching $123.3 billion, according to data from Artemis. That represented a roughly 53.9% increase from the previous high set in September. The number of trades also hit a record of 642.9 million.
Kalshi drove most of the activity, generating $98.2 billion in volume, about 80% of the sector, and processing 465.5 million trades. Polymarket followed with $20.2 billion in volume and 148 million trades. Nadex crossed $2 billion in monthly volume, while Rothera recorded its second consecutive month above $1 billion.
Sports betting was the largest category, fueled by NFL and college football. Kalshi set three consecutive weekly volume records, with the week ending October 25 exceeding $25 billion. Its parlay product, combos, accounted for 67.6% of Kalshi’s monthly volume. Many of these bets were long shots priced below 1 cent, and because Kalshi records each contract at its full $1 payout value, notional volume can overstate actual money at risk. Trader count growth provides a second signal of expanding engagement.
Political markets also surged ahead of the November 3 U.S. midterms. Midterm-linked prediction market volume passed $1.4 billion, with Kalshi accounting for nearly $1.1 billion. As of October 31, Kalshi’s House control market had traded about $170 million and its Senate market about $111 million. A preliminary late-October estimate had put Kalshi’s overall monthly volume at roughly $65 billion, up about 10% from September, before the final record was reached.
Crypto-based contracts were another bright spot. Combined crypto volume on Kalshi and Polymarket crossed $3 billion for the first time in October and repeated the feat two weeks in a row. Kalshi’s 15-minute Bitcoin up/down contract stood out, allowing traders to bet on whether BTC finishes higher or lower within a quarter of an hour. Polymarket’s regulated U.S. platform also set a monthly high of nearly $10 billion, about 15% above its previous record, and combos grew to more than 20% of its volume.
Kalshi operates as a CFTC-regulated designated contract market. The surge has drawn attention to election-contract transparency, market integrity and the difference between prediction prices and polling. The company said election-market viewers outnumber active traders by about five to one, and it has added historical forecast-accuracy measures and warnings for low-volume markets. It also cautioned that reported contract volume should not be confused with customer deposits, net investment inflows or exchange revenue.
