In a series of tweets, Twitter chief operating office Adam Bain said he's leaving the company.
Bain said he's excited to do something "totally different and new outside the company" but didn't give specifics.
Twitter's chief financial officer, Anthony Noto, has been named COO effective immediately, Twitter said in a statement Wednesday.
"Mr. Bain will remain at Twitter in the coming weeks to assist with the transition of the chief operating officer role," the company said.
"Adam has built an amazing team and a global business from the ground up,” said Jack Dorsey, Twitter’s CEO, said in a written statement. “I’m grateful to Adam for everything he’s done for Twitter, and for his leadership and friendship over the years."
In recent quarters, the growth of Twitter’s ad business has slowed and Bain has had to grapple with a more challenging digital advertising environment.
Bain's departure comes nearly two weeks after the company announced a new round of layoffs, which had been widely rumored, including in the sales division he oversaw. Bain is joining a list of several key figures, such as product head Kevin Weil, who left Twitter this year.