• by Laurie Sullivan  @lauriesullivan, June 12, 2014

Ali Rowghani, Twitter COO since Dec. 2012, and CFO before that, has resigned from his position, but will continue in an advisory role to the CEO.

The U.S. Securities and Exchange Commission filing states: "Twitter does not intend to hire a replacement for the COO role, and all of Mr. Rowghani's operating responsibilities will be assumed by other members of the Twitter management team."

eMarketer estimates that Twitter will increase its user base nearly 25% this year, with most of the growth coming from Asia-Pacific. Today, nearly one-third of Twitter's users are in the Asia-Pacific region.

Twitter accounted for 0.5% of global digital ad revenues in 2013, up from 0.3% in 2012, according to eMarketer. Twitter's share will increase to 0.8% this year, as digital ad spending grows to $137.53 billion, per the analysis firm.

While there's plenty of room to grow, mobile dominates Twitter's ad revenue, with 72% of the company's worldwide net ad revenue coming from mobile devices last year, and an estimated 76% this year, per eMarketer.

The projected growth has not stopped Twitters execs from flying the coop. Some might call it a Twitter shakeup. In May, Twitter engineering senior vice president Chris Fry resigned; he had been in the role since March 2013. His responsibilities moved to vice president Alexander Roetter. The SEC filing states Fry moved to an advisor. Roetter was a software engineer at Google, where he worked on the founding team for AdSense and later on several systems and ad quality projects.