His Job Whittled Down, Twitter's No. 2 Resigns

SAN FRANCISCO - Twitter's chief operating officer, Ali Rowghani, resigned on Thursday, after months of watching his responsibilities shrink at the social networking company.

Twitter said in a securities filing that it did not intend to appoint anyone else to that position.

Mr. Rowghani, who joined Twitter in 2010 as chief financial officer, ascended to the No. 2 spot a couple of years later. Although his duties varied, he had recently overseen efforts to grow the micromessaging service, by attracting new users and increasing activity among existing users.

But those efforts failed to produce sufficient results, sending Twitter's stock plunging.

The company's chief executive, Dick Costolo, decided to take a more direct role in trying to fix the problems. Mr. Costolo pushed out the top product and engineering executives, and he realigned the organization chart so that their replacements reported directly to him.

Mr. Rowghani oversaw Twitter's successful efforts to court television networks and Hollywood, and he helped turn Twitter into a hub for entertainment chatter. But much of the growth in that area has come from the advertising side of the company, overseen by Adam Bain and Kevin Weil. Mr. Costolo has gradually given them a bigger role as the company makes a big business out of Twitter messages sent during live television events.

That left Mr. Rowghani, a former Pixar executive who was once viewed as a potential successor to Mr. Costolo, with little to do.

Mr. Rowghani has been selling Twitter shares heavily since May, when insiders were first allowed to sell after the company's initial public offering in November.

In a parting tweet, Mr. Rowghani wrote, 'Goodbye Twitter. It's been an amazing ride, and I will cherish the memories.'

Mr. Costolo responded publicly on Twitter: 'Thank you for being an incredible executive & partner. Twitter could not have succeeded without you.'

Through a spokesman, both declined further comment.

The company said Mr. Rowghani would remain an employee and strategic adviser.