U.S. Treasury prices rallied Wednesday, pushing benchmark 10-year yields to a new 15-month low, as the probability of a win in the November presidential election by Democrat Kamala Harris rose after a televised debate against Republican Donald Trump.

Ten-year Treasury yields dipped to a session trough of 3.609% as prices rose, the lowest since June 2023.

The debate gave investors little clarity on key policy issues, even as betting markets swung in favor of Harris after the event.

Goldman Sachs last week said the U.S. economy would likely get a bigger boost over the coming two years from a Harris win, while a Trump win would undermine growth mostly due to increased tariffs. Analysts also expect a Trump win to add more to debt levels.

Investor sentiment was fragile on Wednesday, creating a bid for safe-haven government bonds and low-yielding currencies such as the Japanese yen and the Swiss franc and weighing on U.S. stock futures.

Deutsche Bank strategist Jim Reid said it was "clearly impossible to isolate the direct impact of the debate."

"The market for now seems to have some agreement with the probabilities above as to how the debate went. We will see how it resonates from here," he said.

Focus now turned to the release of monthly U.S. consumer inflation data later in the session.

Two-year Treasury yields fell just over 4 bps to around 3.56%.