SAN FRANCISCO — Twitter bumped up Adam Bain to chief operating officer on Monday, giving him greater responsibilities as the No. 2 executive to new chief executive Jack Dorsey.

The well-liked revenue chief, who built the company’s advertising business and was himself a contender to become CEO, will be Dorsey’s right-hand executive and help him juggle demands at Twitter and at digital payments company Square, where Dorsey is also CEO.

Bain, 42, who hailed from News Corp.’s Fox Sports and Fox Interactive Media unit, joined Twitter in 2010, when it had a small sales team and few ad products. On his watch, Twitter increased revenues from $28.3 million in 2010 to more than $1.4 billion in 2014 and is expected to surpass $2 billion this year.

“I am honored to be asked to take on added responsibilities,” Bain said. “I’ve worked in partnership with Jack since I joined Twitter in 2010. Over the last three months, that partnership has only gotten stronger as has my conviction that Jack is the right person to run the company.”

Bain also reaffirmed his commitment to Twitter.

“We don’t have to guess about how Jack will do as CEO, we have already seen him in action for a quarter and his impact is clear,” said Twitter investor Chris Sacca. “Underpinning my confidence in Jack as CEO is the promotion of Adam Bain to COO. No one in business is more liked, more admired and more effective than Adam. He has been a CTO and a Head of Product as well as a Chief Revenue Officer over the course of his career. He understands best how to pull a team together to get stuff done, make users happy, and make money along the way.”

Pressure is building on Bain as revenue growth rates slow. In July, Twitter reported its smallest quarterly revenue growth as a publicly traded company.

In the second quarter Twitter beat Wall Street estimates with $502 million in revenue, a 61% year-over-year jump. That followed an unexpected revenue shortfall when Twitter blew Wall Street’s and its own projections. Twitter has yet to post a profit.

The central challenge facing the new Dorsey/Bain ticket: Twitter must reassure investors amid flagging user growth and questions about its future prospects.

“The single biggest reason why Adam Bain is important to Twitter is because he has been able to keep the revenue stream going even in the face of all of Twitter’s challenges,” Debra Aho Williamson, an analyst at research firm eMarketer, told USA TODAY in August.

Now Bain will assume additional responsibilities as Dorsey’s No. 2 in addition to overseeing Twitter’s advertising business and revenue efforts, board member Peter Currie said.

A happy-go-lucky workaholic who barely sleeps at night, Bain already oversaw more than half of Twitter’s 4,100-strong workforce.

Bain leads Twitter’s business efforts around the globe. He cuts deals with mobile carriers, cable companies, app stores, game consoles and wearable companies. He’s also responsible for the company’s strategic relationships with technology giants such as Apple, Samsung, Microsoft and, importantly, Google. Earlier this year Twitter clinched a deal to give Google access to its stream of data, making it easier for tweets to appear in search results.

Bain’s main achievement is the company’s advertising business. Twitter now can place ads on Twitter and off Twitter, serving as a middle man to match advertisers with ad space on other mobile apps. Its mobile ad business accounted for 88% of ad revenue in the second quarter. Twitter is also very focused on small- and medium-sized businesses, which has emerged as its fastest-growing business line.

“He knows what advertisers want and he knows how to deliver what advertisers want. And that is what he has been doing in a steady way throughout everything swirling around Twitter,” Williamson says. “Ad revenue is still growing. Advertisers are still very intrigued about what they can do on Twitter.”

Bain has a close relationship with Dorsey. Long before Dorsey took on the interim and then permanent CEO role, Bain met with him each week to discuss the state of the company’s business, product direction and its future.

Follow USA TODAY senior technology reporter Jessica Guynn @jguynn.

Read or Share this story: http://usat.ly/1RrbsOy