(Bloomberg) — Tucker Carlson, one of the most popular Fox News prime-time hosts, was worth more than $590 million to the parent company. At least that is what trading in the stock indicates.

Class A shares of Fox Corp. sank as much as 5.4% Monday, the most since October after the company said Carlson had left with immediate effect. The departure comes just days after the network agreed to pay $787 million to settle a defamation suit brought by Dominion Voting Systems Inc.

“Fox Cable News is now in rebuilding mode, and it will likely take time for the stock to recover,” said KeyBanc Capital Markets analyst Brandon Nispel. “With the advertising upfronts right around the corner in May, we wonder what Fox is going to tell advertisers and how it will fill the gap in terms of programming and viewership.”

Excluding sports, Tucker Carlson Tonight is the top-rated prime-time show on cable TV, according to the most recent Nielsen ratings, with a nightly audience that at times exceeded 3.7 million viewers. That said, the channel is likely to regain the majority of its overall viewership once a replacement host is announced, Nispel said.

Carlson’s exit is “definitely going to leave a mark on Fox,” said Matthew Tuttle, CEO and CIO of Tuttle Capital Management, who bought shares of Rumble.