Ex-NBCUniversal advertising executive Linda Yaccarino will take over as CEO of Twitter, Elon Musk said on Friday.

Musk, who runs Tesla and Space X, said a day prior that he plans to transition to a role as executive chairman and chief technology officer.

Yaccarino "will focus primarily on business operations, while I focus on product design & new technology," Musk said on Friday. "Looking forward to working with Linda to transform this platform into X, the everything app," he added.

The announcement comes months after Musk pledged in December to step down as the head of Twitter as soon as he found someone "foolish enough to take the job."

Yaccarino, who stepped down earlier on Friday as the ad sales chief at NBCUniversal, oversaw an international team of about 2,000 employees, according to the NBCUniversal website.

She brings longstanding relationships with major advertisers and a strong reputation within the corporate community, experts told ABC News.

"She transformed advertising at NBCUniversal," Mike Proulx, a vice president and research director at Forrester, told ABC News. "If she succeeds, Twitter succeeds."

This is a developing story. Please check back for updates.