Prediction market volume hit a seasonal high this week as traders rotated capital into a tight cluster of political, economic, and sports contracts heading into the final stretch before the November 2026 midterms. Open interest across Kalshi and Polymarket combined topped $1.9 billion for the seven-day window ending October 13, with Senate control, the Fed’s November rate path, and NFL postseason odds absorbing the majority of order flow.
Here are the highest-volume prediction contracts of the week, where the smart money is positioned, and what the probabilities are telling us about the next 30 days.
Senate Control Dominates Political Volume
The “Which party will control the Senate after the 2026 midterms?” market remains the single highest-volume political contract on both venues. Combined notional traded this week crossed $340 million. Republican control is pricing at 58%, with Democratic control at 41% and a 1% tail for a 50-50 split dependent on the Georgia and Pennsylvania runoff windows.
Movement was concentrated in two specific state-level contracts. The Ohio Senate race shifted from 54% to 61% in favor of the Republican candidate following the final debate, while the Arizona Senate contract tightened from a 12-point Democratic lead to just 4 points. Traders are treating Arizona as the likely tipping-point state, and spreads there have narrowed to under 2% as market makers add depth.
Fed Rate Decision: 25bp Cut Pricing at 67%
The November FOMC market absorbed heavy flow after the September CPI print came in at 2.4% year-over-year, modestly below consensus. A 25 basis point cut now prices at 67%, with no change at 28% and a 50bp cut at 5%. One week ago, the no-change scenario was the market favorite at 51%.
This is the sharpest week-over-week repricing in the Fed market since July. Terminal rate contracts for the December 2026 meeting have also moved: traders now assign a 42% probability to the Fed Funds target closing the year between 3.75% and 4.00%, up from 29% last week. The implication is that prediction market participants expect the committee to deliver one cut this month and signal a second in December, pending the October payrolls release.
NFL and NBA Volume Accelerates
Sports contracts dominated non-political volume. The NFL Super Bowl LXI futures market saw $186 million in weekly volume with the Kansas City Chiefs leading at 14%, followed by the Buffalo Bills at 12% and the Baltimore Ravens at 11%. The Philadelphia Eagles contract moved the most, climbing from 7% to 10% after a 4-1 start.
On the NBA side, the newly listed “2026-27 NBA Champion” contract hit $94 million in opening-week volume. The Boston Celtics are the favorite at 18%, with the Oklahoma City Thunder at 15% and the Denver Nuggets at 11%. The spread between the top three teams is the tightest in five seasons of NBA prediction market data, reflecting genuine uncertainty rather than one dominant frontrunner.
Bitcoin and AI Milestone Markets
Crypto-linked contracts continued to attract rotational flow. The “Will Bitcoin close above $120,000 by December 31, 2026?” market prices at 54%, down from 61% last week after BTC pulled back below $108,000 mid-week. The “Will Ethereum close above $5,000 by year-end?” contract sits at 38%, essentially unchanged.
In AI, the “Will a frontier lab release a model exceeding GPT-6 benchmarks before Q1 2027?” contract traded $41 million this week and currently prices at 44%. Volume there has grown every week since the contract listed in late August, suggesting a durable new category rather than a short-term fad.
What the Volume Tells Us
The ratio of political-to-sports volume this week was roughly 1.4 to 1, the highest since the 2024 presidential cycle. That is a reliable signal that mainstream participation is rising ahead of election day. Market makers on both venues have widened quoted sizes on tipping-point Senate contracts, which typically indicates confidence that liquidity will hold through November 3.
Expect open interest to continue climbing through late October as hedging flows arrive from political action committees and institutional desks that use prediction markets as a liquid alternative to options on election outcomes.
Where to Trade
Both Kalshi and Polymarket list the full set of contracts covered above. Kalshi offers CFTC-regulated access to US election, Fed, and economic markets with same-day settlement. Polymarket covers a broader slate including crypto, AI, and global geopolitics with deeper liquidity on long-tail contracts.
- Trade these markets on Kalshi — regulated US venue, strong on political and economic contracts
- Trade these markets on Polymarket — deepest crypto and global coverage
- See our full ranking of the best prediction markets in 2026
Volume this week confirms that prediction markets are now a primary venue for pricing election, macro, and sports outcomes in real time. The next 30 days will likely bring the highest weekly notional on record as midterms close in.