After Kamala Harris’ strong performance in her presidential debate against Donald Trump, her chances of election improved across prediction market platforms.
On Polymarket, Harris’ price of presidential victory was 47 cents at the debate’s start and rose to 49 cents the next morning. Her Manifold Market’s price rose one cent after the debate while Trump’s fell one. On B.E.T., her victory price swung 2.6 cents from 47.8 cents to 50.4 cents. Finally, her “Yes” price on PredictIt rose from 53 cents to 57 cents.
Each of Harris’ gains was accompanied by decreases in Trump’s prices of victory. So, her forecasted margins of victory on the prediction market platforms grew noticeably:
| Platform | Harris/Trump Pre-Debate Spread | Harris/Trump Post-Debate Spread |
|---|---|---|
| Polymarket | Trump +5 | Trump +2 |
| Manifold Markets | Harris +3 | Harris +5 |
| B.E.T. | Trump +5.1 | Harris +0.6 |
| PredictIt | Harris +5 | Harris +13 |
Presidential Debates and Reaching Undecided Voters
Both candidates included answers that appealed to their bases. Trump pivoted to crime and immigration on many answers. Harris railed against the medical consequences of abortion restrictions. She also challenged Trump’s support for democracy in his role in the Jan. 6 attack on the Capitol and his lukewarm support for Ukraine in its war against Russia.
However, Harris spent more time speaking on a broader range of issues than Trump. She spoke longer on the economy both defending her positions and attacking Trump. The same was true for abortion, democracy, foreign policy, Jan. 6, race, and China.
Trump’s frequent pivots to recycled attack lines left Harris room to address issues important to undecided voters. Consequently, prediction markets saw Harris’ chances improve and Trump’s odds worsen.
The Sept. 10 debate won’t be the only flashpoint for the fight between Harris and Trump. However, it revealed weaknesses in Trump’s campaign that Harris could continue exploiting between now and Election Day.
