Less than a week ago, Donald Trump looked like a safe bet on prediction markets as polling data continued to shift in his favor, but not anymore.
With just two more days until Election Day, PredictIt now has Kamala Harris in the lead, with a contract that has her winning priced at 54 cents on Sunday, up from 46 cents on Tuesday and 42 cents a week ago. Trump's winning contract is now priced at 51 cents, down from 60 cents on Tuesday.
According to Kalshi, Trump's odds of winning were at 51% on Sunday with Harris at 49%. That's down sharply from Tuesday, when Trump was as high as 64.6% and Harris was as low as 35.4%.
Similarly, the new IBKR Forecast Trader from Interactive Brokers put Trump's odds at 54% on Sunday, down from 68% on Tuesday. Harris jumped as high as 54% on Sunday before easing to 48% later in the day—both up from 37% on Tuesday.
The Harris surge was so dramatic on IBKR that Thomas Peterffy, the founder and chairman of Interactive Brokers, put out a statement on Friday commenting on it.
"Last night, Kamala Harris engineered a surprisingly ferocious comeback on IBKR’s ForecastTrader platform," he said, noting that an 8-point surge in one day was backed by trading volume of about $40 million.
While skeptics of prediction markets have warned that they are vulnerable to manipulation, he said doing so is a crime and is unlikely to have caused the sudden improvement in Harris's odds on IBKR. Instead, Peterffy attributed it to reporting on news events.
According to Thomas Miller, a data scientist at Northwestern University, a turning point came last Sunday during Trump’s rally at Madison Square Garden. That’s when comedian Tony Hinchcliffe called Puerto Rico “a floating island of garbage in the middle of the ocean,” sparking a massive backlash that continued throughout the week.
He told Fortune recently that since the rally, Trump has been suffering an historic collapse that could result in Harris winning the election.
Also bolstering Harris's prospects was Saturday's closely watched Des Moines Register/Mediacom Iowa Poll conducted by Selzer & Co. that showed Harris leading Trump 47% to 44% among likely voters.
That’s flipped from September, when the poll showed Trump with a 4-point lead over Harris, and could signal growing support for Harris elsewhere in the region, like the key swing states of Wisconsin, Michigan, and Pennsylvania.
And on Sunday morning, the New York Times/Siena College poll of battleground states showed that the race is still close but with last-minute deciders breaking toward Harris.
Still, the recent twists come after a month of largely positive polling data for Trump while more than 70 million voters have already cast their ballots.
The latest polling analysis from 538 gives Trump a 53-in-100 chance of winning the election versus 47 out of 100 for Harris, which is the same as a week ago.
And José Torres, senior economist at Interactive Brokers, wrote in a note on Friday that a Republican sweep of the White House, Senate, and House of Representatives is still narrowly favored in the IBKR forecasting model.
