U.S. health insurers quickly jumped to their highs of the day after Senator Amy Klobuchar ended her bid for the presidency and said she plans to endorse former Vice President Joe Biden for the Democratic nomination.

Humana Inc., UnitedHealth Group Inc., Anthem Inc. and Molina Healthcare Inc. advanced at least 1.7% each, spurring the seven-member index of S&P managed care companies toward its best day in almost three weeks. The intraday rally comes as investors leaned into bets that Klobuchar’s backers will side with Biden, and not Senator Bernie Sanders.

Sanders’s potential ascendancy is something Wall Street has warned could impact the health sector, and most notably those in the managed care space. Sanders’s push for a single payer health system, known as Medicare for All, would make health insurers among those most vulnerable to a Sanders presidency.

The index is down more than 10% so far in 2020, despite Monday’s 4.6% rally, as investors weigh who will challenge President Donald Trump in November. The drop stands in contrast to the S&P 500 Index’s roughly 6.7% decline this year.

This article was provided by Bloomberg News.