With just two days until Election Day, PredictIt now has Kamala Harris in the lead, with a contract that puts her winning price at 54 cents on Sunday, up from 46 cents on Tuesday and 42 cents a week ago. Trump’s winning contract now costs 51 cents, up from 60 cents on Tuesday.

According to Kalshi, Trump’s chances of winning on Sunday were 51% and Harris’s were 49%. That’s down sharply from Tuesday, when Trump was at 64.6% and Harris was at 35.4%.

Similarly, Interactive Brokers’ new IBKR Forecast Trader put Trump’s odds at 54% on Sunday, up from 68% on Tuesday. Harris rose to 54% on Sunday before falling to 48% later in the day – both up from 37% on Tuesday.

The Harris wave was so dramatic at IBKR that Thomas Peterffy, the founder and chairman of Interactive Brokers, issued a statement commenting on it on Friday.

“Last night, Kamala Harris pulled off a surprisingly ferocious comeback on IBKR’s ForecastTrader platform,” he said, noting that an 8-point gain in one day was supported by trading volume of about $40 million.

While skeptics of prediction markets have warned that they are vulnerable to manipulation, he said this is a crime and is unlikely to have caused the sudden improvement in Harris’ odds on IBKR. Instead, Peterffy attributed it to coverage of 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. Then comedian Tony Hinchcliffe called Puerto Rico “a floating trash island in the middle of the ocean,” sparking a huge backlash that lasted all week.

He told it Fortune recently that Trump has suffered a historic collapse since the rally that could lead to Harris winning the election.

Strengthening Harris’ prospects was also closely watched on Saturday Des Moines Register/Mediacom Iowa Poll conducted by Selzer & Co. which showed Harris ahead of Trump by 47% to 44% among likely voters.

That has reversed from September, when the poll showed Trump with a four-point lead over Harris, and could indicate growing support for Harris elsewhere in the region, such as the key swing states of Wisconsin, Michigan and Pennsylvania.

And on Sunday morning, the New York Times/Siena College polls of battleground states showed the race still close, but last-minute deciders are breaking toward Harris.

Still, the recent twists come after a month of largely positive polling for Trump, with more than 70 million voters having already cast their ballots.

The latest polling analysis of 538 gives Trump a 53 in 100 chance of winning the election, compared to 47 in 100 for Harris, which is the same as a week ago.

And José Torres, senior economist at Interactive Brokers, wrote in a note Friday that a Republican attack on the White House, Senate and House of Representatives is still narrowly favored in the IBKR forecast model.

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