Dick CostoloAmid mounting pressure from investors from Wall Street, Dick Costolo has stepped down from his role as chief executive officer of microblogging platform Twitter after five years and the company’s co-founder and chairman Jack Dorsey will take over as interim CEO.

The Wall Street Journal reports that the company will be searching for a new CEO both internally and externally. The search committee will include board members Peter Currie, Peter Fenton and co-founder Evan Williams. Interestingly, Jack Dorsey, who is also CEO of payments company Square Inc, will not be on the committee to find a new chief.

It’s worth noting that one of Twitter’s earliest investors Chris Sacca recently wrote a really long blog post about the microblogging site, and said among many, many other things that “Twitter has been unable to convince investors of its potential upside” and “Wall Street’s confidence in the management team has diminished.”

Under Costolo’s stewardship, the company has been trying hard to acquire new users on its platform and has been acquiring a number of companies to give new product offerings. For the quarter ended March 31, Twitter reported 302 million monthly active users globally, reflecting a growth of 18% year-on-year. Rival social networking site Facebook on the other hand reported 1.44 billion monthly active users in the same quarter.

In a recent conference call, Twitter said that it has prioritzed emerging markets as a growth vehicle and added a new set of users known as SMS fast followers.  These are users who sign up and access Twitter solely via SMS. The number of SMS fast followers in the quarter was approximately six million. Twitter CFO Anthony Noto said that they are not currently counting these fast followers but going forward they will be adding them to their user base.

Costolo was responsible for turning the company around from a young struggling startup with in-fighting between the co-founders to a public company. Twitter has since then evolved from a microblogging to a cultural phenomenon and an indispensable tool for journalists and citizens. But following the company’s IPO,Costolo struggled to retain top management which lead a series of exits including chief operating officer Ali Rowghani and chief financial officer Mike Gupta.

Recently, Twitter has hired Anthony Noto, a former Goldman Sachs investment banker who helped the company during its IPO, as its CFO. Noto has been instrumental in allaying some of investors concerns and has been reportedly leading a number of acquisitions for Twitter. The company is reportedly in talks to buy news aggregator magazine Flipboard in an all stock deal which values the company at $1 billion.

Recent acquisitions by Twitter

– Twitter also announced that it has acquired TellApart, a marketing technology company providing retailers and e-commerce advertisers with cross-device retargeting capabilities through dynamic product ads and email marketing.

– Twitter bought Bangalore-based mobile marketing & analytics platform ZipDial which it bought earlier this year. Twitter and ZipDial had developed a platform where users could get could receive tweets from a Twitter account via SMS by dialing a phone number. Rishi Jaitly, head of Twitter India, had said that similar approaches would be now developed to provide a “taste” of Twitter to those with limited internet access and tempting them to download their app.

– Earlier in March, Twitter acquired livestreaming application Periscope. Interestingly Costolo is betting big on Periscope’s adoption and said that one million people signed up with Periscope within the first 10 days of the application’s launch. Costolo also mentioned that people have started using Periscope to broadcast streams of videos of the recent Baltimore riots.

Twitter removes cap on direct messages

Twitter also announced that its is removing the 140 characters cap on direct messages and increased it to 10,000 characters. A Wired report puts that number into perspective: “A seven-page longread I’m currently working on in Google Docs is 13,445 characters. It’s so long I can’t even remember what the beginning said. You could fit a short novel in a DM.” But this could mark a shift in the company’s strategy to a messaging platform.

Earlier in January, Twitter introduced group ‘Direct Messages’ to its platform and introduced features to capture, edit and share videos via its mobile app.

With Direct Messaging users can now start private conversations with other users. Essentially, the platform works just like an other group messaging app, letting you select up to 20 people to chat  with privately in one ‘room’. Even if the people invited to the group don’t follow each other, they are notified when they are added to the group, and when messages are sent.