93 percent odds on the House, the Senate is the real bet

Eleven days before the US midterms of November 3, 2026, traders on Polymarket give Democrats a 93 percent chance of winning the House of Representatives. For the Senate, it is 69 percent. That gap tells you more about your investments than the question of who wins. What everyone already expects is largely in the prices.

Prediction markets already count on a Democratic House

In the midterms, the elections halfway through a presidential term, Americans choose all 435 members of the House and 35 of the 100 senators. Whoever reaches 218 seats controls the House. Right now Republicans hold 218 and Democrats 214. In the Senate, Republicans have a 53 to 47 majority.

The polls point one way. The Decision Desk HQ model gave Democrats a 78 percent chance of taking the House on October 21, with 236 seats, NewsNation reports. A month earlier it was 70 percent. Nate Silver's polling average shows Democrats ahead nationally by 8.6 points, at 49.7 to 41.1 percent, according to Forbes.

What does that mean? On a prediction market you buy a contract that pays 1 dollar if an outcome happens and nothing if it does not. If that contract costs 93 cents, traders put the odds at 93 percent. Polymarket runs on crypto and settles in the stablecoin USDC. As a platform it has an interest in people trading on these outcomes.

If so many people already count on a Democratic House, what is left to discover on election night?

Being right about the obvious pays almost nothing

The payout shows how sure the market is. For the House, Polymarket shows a $100 stake turning into $108 on a correct call. For the Senate, a correct call turns $100 into $145.

In numbers: Convert it to euros and ignore fees and exchange rates for a moment. Put 100 euros in at a price of 93 cents and, if you are right, you get back about 108 euros, so 8 euros of profit. At 69 cents that becomes about 145 euros, so 45 euros of profit. If you are wrong, you lose your 100 euros in both cases.

That is exactly how a stock market treats news. An outcome traders already expect moves little when it arrives. Prices mostly move on surprises, as explained in Why markets sometimes fall when nothing happens. So for an investor the question is not who wins. The question is where the uncertainty still sits.

Trading on such a market is not investing in a company, by the way. You win or lose your stake on a single outcome. In the Netherlands the Kansspelautoriteit supervises online gambling, in Belgium the Kansspelcommissie does.

The Senate is the real bet

Decision Desk HQ gives Democrats a 56 percent chance of winning the Senate, with 51 seats. The chance they win both chambers is 54 percent. A Democratic House with a Republican Senate gets 24 percent, and Republicans holding both gets 21 percent.

Of the four Senate races the model rates as toss ups, races that could go either way, three are in states Trump won by double digits in 2024: Texas, Iowa and Ohio. If the Senate ends up 50 to 50, Vice President JD Vance casts the deciding vote.

A 56 percent chance is not a result: in almost half of cases it turns out differently. 2018 showed how hard a midterm can swing. In September that year Trump was about 12 points underwater, meaning far more voters disapproved than approved. Republicans lost 41 seats that November, Yahoo writes.

So why does the Senate matter so much for your money?

A Democratic House changes the budget, not the veto

Under the US Constitution a law needs both chambers and the president's signature. Overriding a veto takes two thirds of the votes in both chambers. With 236 of 435 seats, the Decision Desk HQ projection, Democrats come nowhere near that.

That shapes what happens to the economy. The Constitution gives Congress the power to impose import duties. Trump imposed his tariffs through powers Congress had earlier handed to the president. A Democratic House can vote to limit those tariffs, but without the Senate and without two thirds, the president keeps the final word.

Immigration works the same way. The immigration agency ICE received extra money through the One Big Beautiful Bill Act, and that law stays in place. But every year a new budget is needed, and that takes both chambers. That is where a Democratic House has power: it can attach conditions to money for border enforcement. Whether you call that open borders or tighter oversight is a political question.

Watch out: A divided Congress means more budget fights. Without a deal, the government partly shuts down and official data on jobs and inflation comes out later. Those are exactly the figures the Federal Reserve uses for its rate decisions.

And the Fed brings you straight back to the Senate.

The Senate votes on who sets interest rates

Every governor of the Federal Reserve, the US central bank, is nominated by the president and must be confirmed by the Senate. A Democratic Senate could block or delay Trump's candidates. The House has no say in this.

For investors that is no detail. Fed rates feed into the dollar, US government bonds and stock valuations. Whoever holds the Senate has a say in who sits at those controls. That applies to crypto too, but there something else is at play.

For crypto, what has not passed the Senate matters most

The stablecoin law, the GENIUS Act, is already law. A new majority could only reverse it with both chambers and the president, so it stays. How these coins work is covered in our piece on stablecoins.

The CLARITY Act is a different story. That bill decides which regulator oversees which coin, the securities regulator SEC or the futures regulator CFTC. The House already passed it, but without the Senate it does not become law. Bills that are unfinished when the current Congress ends in January expire. The new Congress then has to start over, with a different makeup.

Tip: Look up the CLARITY Act on Congress.gov under number H.R.3633 and open the Actions tab. There you can see by date what has happened to the bill and whether the Senate has voted. That tells you which news the market does not know yet.

So the weeks between the election and January count. What the crypto market did this month is in the October crypto week.

Europe feels it through tariffs and the dollar

For the Netherlands and Belgium the effect runs mainly through trade. Trump's tariffs drew criticism from economists and world leaders for worsening inflation. Since the war with Iran began on February 28, gasoline prices have also shaped the campaign. On top of that there are disputes with Europe, such as over Starlink, covered in US threatens Europe over Starlink.

A Democratic Congress can hold hearings and open investigations, but trade policy largely stays with the president. European exporters will not automatically face different tariffs after November 3.

Example: Say you invest in the S&P 500 through an ETF. If the index rises in dollars but the dollar falls against the euro, you see less return in euros, or even a loss. Elections that shift expectations about US interest rates reach you through the exchange rate too.

These questions help you around November 3

• Which outcome is already in the price, and what would be a real surprise?
• Does the winner hold a majority in both chambers, or does the veto keep the final word?
• Does the CLARITY Act clear the Senate before January, or does the new Congress start over?
• How much of your portfolio is in dollars, and what does a weaker dollar do to your return in euros?
• Does a prediction market you come across fall under the gambling rules in your country?

This text is an explanation, not financial advice.

Sources

• NewsNation, Democrats narrowly favored to sweep House and Senate: DDHQ, October 22, 2026
• Forbes, Hottest 2026 Midterm Races, October 21, 2026
• Yahoo News, The 2026 midterms are just 12 days away, October 22, 2026
• Polymarket (trading platform with its own interest), 2026 Midterms Election Odds & Predictions, accessed October 23, 2026
• Wikipedia, 2026 United States House of Representatives elections, accessed October 23, 2026
• Wikipedia, 2026 United States elections, accessed October 23, 2026
• Congress.gov, H.R.3633 CLARITY Act, accessed October 23, 2026
• Congress.gov, S.1582 GENIUS Act, accessed October 23, 2026
• Federal Reserve, Structure of the Federal Reserve Board, accessed October 23, 2026
• Constitution Annotated (Congress.gov), Article I Section 7, accessed October 23, 2026
• Constitution Annotated (Congress.gov), Article I Section 8, accessed October 23, 2026