On the other hand, it is not clear how long advertisers intend to stay away from O'Reilly, or what the short-term financial effect, if any, will be. Sponsors tend to buy cable ads in blocks, so removing an ad from one program usually means it is simply moved to another time slot, making little financial difference. What is more, cable-news channels derive the bulk of their revenue from licensing fees paid by cable and satellite operators, not advertising.
Despite knowledge of his multiple settlements, Fox and its parent company, 21st Century Fox, have stood by O'Reilly. The parent company last week re-signed the combative host to a new long-term contract that will pay him a reported US$18 million per year and keep him on the air until at least 2020.
The advertisers who pulled out of O'Reilly's program said they were responding to a New York Times story published Saturday that found the host and the network have separately or jointly paid at least US$13m to five female employees in exchange for their promise not to sue or publicly discuss their cases against O'Reilly. A sixth woman, former "O'Reilly Factor" contributor Wendy Walsh, said that O'Reilly had sexually harassed her, too, but that she did not intend to sue or seek compensation.
"While it's hard to tell what the facts are, the allegations are disturbing," said Donna Boland, a spokeswoman for Mercedes-Benz. "Given the importance of women in every aspect of our business, we don't feel this is a good environment in which to advertise our products right now."
Untuckit's co-founder and chief executive, Aaron Sanandres, had a similar comment: "As a company in which more than two-thirds of our employees are women, we take sexual harassment claims very seriously. . . . In light of the disturbing allegations, we instructed our media buyer this morning to reallocate our ad dollars to other shows effective immediately."
The harassment complaints against O'Reilly are on top of a separate wave of allegations against Roger Ailes, Fox News's co-founder. The allegations surrounding Ailes came to light after Gretchen Carlson, a former Fox host, filed a lawsuit in July alleging that Ailes had pressured her for sex and demoted her when she refused.
The suit touched off an internal investigation that brought forward other complaints and led to Ailes's ouster as chairman of the network. Carlson received US$20m from Fox to settle her suit. Ailes, who has denied the allegations, received US$40m in severance.
At the time, Fox and 21st Century asserted that it had "zero tolerance" for sexual harassment.
But Fox has struggled to put the issue behind it. On Monday, a Fox News contributor named Julie Roginsky filed another sexual-harassment suit against Ailes and his former top lieutenant, Bill Shine. In response, the network's top human-resources executive, Kevin Lord, issued a companywide memo that read, in part, "If any employee has any concerns about behavior in our workplace, I urge you to raise those concerns with me" and other company executives.
The mounting harassment allegations paint Fox as "the next Bill Cosby," said Eden Gillott Bowe, who heads a communications firm that represents celebrities, athletes and nonprofit organizations facing adverse publicity.
"It's death by a thousand cuts," she said. "Until Fox can clean house, until they can make changes in good faith, I think they'll keep hemorrhaging advertisers. They need to make a clean break," even by taking the painful step of suspending or firing O'Reilly.
As the advertiser backlash grew Tuesday, both Fox and 21st Century Fox were muted in their defense of O'Reilly throughout most of the day. In the past, both have been quick to defend him.
Late in the afternoon, Fox issued a statement from its executive vice president of advertising sales, Paul Rittenberg, reading: "We value our partners and are working with them to address their current concerns about the O'Reilly Factor. At this time, the ad buys of those clients have been re-expressed into other FNC programs."
21st Century referred to a statement it issued after the Times article in which it said it "takes matters of workplace behavior very seriously." It said "no current or former Fox News employee ever took advantage" of a company hotline to raise concerns about O'Reilly, "even anonymously."
O'Reilly did not address the unfolding controversy around him on his program Tuesday.
In a statement over the weekend, he defended himself, saying, "I'm vulnerable to lawsuits from individuals who want me to pay them to avoid negative publicity." He said he settled the cases because "I'm a father who cares deeply for my children and who would do anything to avoid hurting them in any way. And so I have put to rest any controversies to spare my children."