For Fox News, it was another unkind week in an unkind year.

The network’s founding chairman, Roger E. Ailes, died on Thursday, sending a shock through a newsroom still reeling from a string of harassment scandals, lawsuits and high-profile departures. The threat of a federal investigation into the network’s financial practices has lingered.

And on Friday, another prominent on-air personality was abruptly tossed. Bob Beckel, a co-host of the prime-time talk show “The Five,” was fired after an African-American employee accused him of making a racially insensitive remark.

The drumbeat of tough headlines has taken a toll on morale at Fox News, with employees on and off camera describing a feeling of being under siege.

And after years as the undisputed king of cable news, Fox News ranked third in prime-time this week among the 25-54 age group most important to advertisers, finishing behind its rivals MSNBC and CNN. In total audience, MSNBC edged out Fox News in prime-time on three nights, an unsettling sign for an evening schedule scrambled by last month’s exit of Bill O’Reilly.