Polymarket Midterms: How the Odds Called the Senate, and the One Upset They Missed

Polymarket called the 2026 midterms mostly right, and it got there hours before the networks. An hour before the first polls closed, the market gave Democrats a 73.5 percent chance of winning both chambers. NBC News called the House at 04:08 CET and the Senate at 05:26 CET on Wednesday. In the nine Senate races with a Polymarket market that had been called by 05:30 CET, the favourite won eight. The big miss was South Carolina, where Annie Andrews stood at just 30.5 percent.

Polymarket and the midterms: the key facts

• Both chambers: 73.5 percent for a Democratic sweep at 23:00 CET on 3 November, 98.7 percent at 03:00 CET.
• Senate races: eight of the nine races called by 05:30 CET went to the favourite, and more have been decided since.
• Biggest miss: South Carolina, Darline Graham 69.5 percent, Annie Andrews won.
• Coin flip: Iowa, 50.5 to 49.5 percent for the later winner Josh Turek.
• Volume: about $164 million on the three national markets and about $67 million on 14 Senate markets, according to Polymarket.

Polymarket midterms: what the market said before the polls closed

We took the last price before 23:00 CET on Tuesday, one hour before the first polls closed in Indiana and Kentucky, and compared it with the race calls by NBC News up to 05:30 CET. Only called races count here.

Polymarket Senate odds: the miss in South Carolina and the coin flip in Iowa

A favourite at 70 percent is supposed to lose three times out of ten, so one miss proves little. The favourites in these nine races averaged 79 percent, which means about seven wins were to be expected, and it became eight. That is a good night and a small sample at the same time.

The money did not see South Carolina coming. Darline Graham, who was appointed after her brother Lindsey Graham died in July, was priced at 69.5 percent. Kansas was a surprise of a different kind: Adam Hamilton stood at 64.5 percent in a state Trump carried by 16 points in 2024, and NBC News calls his win an upset. Here the market was ahead of the headlines.

How fast the Polymarket odds moved on election night

The odds of a sweep moved long before the networks called anything: 73.5 percent at 23:00 CET, 88.5 at 01:00, 92.5 at 02:00 and 98.7 at 03:00. The House followed at 04:08 and the Senate at 05:26. Bettors were reacting to early counts and county data in real time, and they can be wrong about those too.

Two open races show how the market thinks. At 05:30 CET, the market put Peggy Flanagan at about 99 percent in Minnesota while Michele Tafoya led the partial count, and shortly after 06:00 NBC News called the race for Flanagan: the bettors were right about where the outstanding votes came from. Pete Ricketts stood at about 95 percent in Nebraska while Dan Osborn led, and at 06:00 the count was 47.6 to 46.7 for Osborn. That is the next test, and the reason to treat market odds as odds and not as results.

Why the midterms matter for prediction markets and crypto

Few events show as clearly what crypto rails can carry: bets settled on-chain, open around the clock and visible to everyone while the votes are being counted. Texas alone drew about $21 million. How much this activity means for its host chain is the subject of our Polygon analysis.

That does not make it a product for everyone. In September, the EU regulator ESMA said that marketing event contracts in the EU generally requires an EU authorisation, which the largest platforms lack, as our report on Polymarket and ESMA explains. This article is a look at what the prices said, not a recommendation to bet.

What the midterm result means for Bitcoin

Bitcoin stood at about $76,609 when the Senate was called. The market had priced a sweep for hours, and the debate now turns to rates, oil and regulation. Read our midterm election results live tracker, what the House result means for crypto and what the Senate result means for Bitcoin. Platforms for holding through such nights are in our comparison of regulated crypto exchanges and our crypto broker comparison. This article is not investment advice.