Twitter's Chief Operating Officer Ali Rowghani has decided to step down from his position at the company. He will remain employed by the company and will act as an adviser.

Rowghani won't be replaced and CEO Dick Costolo seeks to be more involved with the company's engineering and product teams.

Rowghani joined Twitter in 2010 as chief financial officer and then moved into the COO role two years later. Before joining Twitter, he was CFO at Pixar Animation Studios for nine years.

Twitter did not reveal the reasons for Rowghani's resignation and said other executives would take on his responsibilities. Twitter follows suit with Apple, Google, Yahoo and Netflix, none of which have COOs.

Rowghani was asked to expand Twitter's user base, but growth in the company didn't happen as quickly as investors wanted. He did well attracting Hollywood companies and television networks, but Twitter's need is for advertising revenue through sponsored tweets.

Even with the success of attracting TV networks and encouraging them to talk about Twitter on the air, NBCUniversal said that Twitter had little effect on increasing TV ratings for the Winter Olympics. The Winter Olympics this year was heavily connected to Twitter, and viewers were constantly reminded to connect with athletes and fans on the service.

Twitter is trying to appeal to more Internet users. Currently, they're trying to lure soccer fans from all over the world to use Twitter to follow the World Cup in Brazil. 

Rowghani's departure could have been predicted. He recently started dumping his shares in the company. He's sold about $12.5 million in shares in the last two months.

Twitter shares have been hit hard recently as the company hasn't been able to report favorable earnings results. However, today they are up sharply, up more than 4 percent on the news of Rowghani's departure.

Speculators are saying that Twitter wasn't happy with Rowghani's performance as a COO.