Mr. Musk said Ms. Yaccarino would focus on business operations and that he would work on product design and technology at the social media platform.
Linda Yaccarino, NBCUniversal’s advertising chief, was preparing to interview Elon Musk, Twitter’s owner, onstage at a conference last month when she received an email from a peer in the advertising industry.
Rob Norman, a former executive at the ad giant WPP, wanted to know if Ms. Yaccarino had seen the op-ed he wrote after Mr. Musk took over Twitter last year. Mr. Norman’s column discussed the tech billionaire’s amplification of misinformation on Twitter and its chilling effect on advertisers.
Ms. Yaccarino said she had and that she planned to raise such concerns, Mr. Norman said. But the main focus of her talk with Mr. Musk would be on something else: His efforts to revamp the social network into “Twitter 2.0.”
Now Ms. Yaccarino is set to become the face of Twitter 2.0. Mr. Musk said on Friday that he has selected Ms. Yaccarino, 60, to become the company’s chief executive. Hours earlier, NBCUniversal had announced that Ms. Yaccarino was leaving, effective immediately, without saying where she was headed.
“I am excited to welcome Linda Yaccarino as the new C.E.O. of Twitter,” Mr. Musk tweeted. He said she would mainly handle business operations while he would continue to work on product design and technology.
In selecting Ms. Yaccarino, Mr. Musk is signaling what he is prioritizing at Twitter: the company’s advertising business, rather than social media know-how. Ms. Yaccarino has been one of Madison Avenue’s power brokers for decades. And Twitter, which makes the bulk of its revenue from ads, has been struggling to grow that business, especially after Mr. Musk spooked advertisers last year.
“Linda’s a force,” said Joe Marchese, the former head of ad sales at Fox Networks Group, where he competed with Ms. Yaccarino for marketing dollars. “She has one of the biggest jobs in advertising, and the ad market is as hard as it’s ever been.”
Yet Ms. Yaccarino will have to do more than contend with Twitter’s advertising woes. The San Francisco company has been severely slimmed down since Mr. Musk slashed 75 percent of its work force and has grappled with gaps in expertise and technical glitches. Twitter also is weighed down by a $13 billion debt load that it took on to enable Mr. Musk to buy the company.
Most significantly, Ms. Yaccarino would have to deal with a mercurial and unpredictable boss in the form of Mr. Musk. Mr. Musk, 51, has a track record of firing executives who don’t achieve his goals. He sometimes tweets news about his companies, including the electric carmaker Tesla, without warning. And as Twitter’s owner, Mr. Musk retains absolute power at the company.
Lou Paskalis, a longtime ad executive and friend of Ms. Yaccarino’s, likened her move to Twitter to taking a “step into the lion’s mouth.”
“With her stature in the industry as probably one of the most beloved and trusted people on the revenue side, I question why she would subject herself to that kind of potential reputational risk,” he said. “If she fails in the role, then there’s probably no way that Twitter will survive as an ad-supported platform.”
Ms. Yaccarino did not return requests for comment, but said in NBCUniversal’s statement that working at the company “has been an absolute honor.”
This is a developing news story and will be updated.
John Koblin contributed reporting from New York.