Prediction market turnover reaches $4.6 billion as Democratic Senate odds rise

DeFi Rate’s odds board recorded $4.6 billion in trading over the last 24 hours across nine prediction market exchanges, according to its update published Oct 31, 2026, at 3:45 PM ET.

Volume measured at $1 per contract

The reported total counts contracts at $1 each. That methodology is important when interpreting the $4.6 billion figure: it reflects the board’s stated contract-counting convention.

The summary provides an aggregate across nine exchanges but does not break out trading volume by platform or individual market.

Democratic Senate odds gain over the week

For Senate control, DeFi Rate reported a 71 percent probability for Democrats across Kalshi and Polymarket, up 5 points on the week.

The Senate reading covers those two named platforms, while the overall volume figure spans nine exchanges. The summary does not specify how much of the reported trading involved Senate-control contracts.

What it means for prediction markets

• Measurement matters: The $4.6 billion total uses a $1-per-contract convention; the summary does not provide a separate measure of cash spent.
• Senate pricing has shifted: The 5-point weekly increase puts the reported Democratic probability at 71 percent, rather than establishing an election outcome.
• The figures have different scopes: Aggregate activity across nine exchanges cannot, from the supplied data alone, be tied to the Senate odds movement on Kalshi and Polymarket.