Twitter Inc. Chief Operating Officer Anthony Noto has resigned to accept the role of chief executive officer at financial technology company Social Finance Inc. Twitter’s shares slipped the most in almost two months.

Noto will assume the post at SoFi in March. His departure comes at a pivotal time for Twitter, which is finally showing results from its turnaround efforts. Since beating Wall Street’s estimates in late October, the company has been upgraded by at least six analysts, who have cited more user engagement and improvements in Twitter’s live video advertising.

Noto’s take-action attitude has been an important balancing presence to CEO Jack Dorsey’s introverted leadership style, according to people familiar with the matter. Losing him may deal a blow to the company’s positive momentum.

Twitter hired Noto, 49, as CFO in 2014 with a stock award worth more than US$60 million, following a career in banking at Goldman Sachs Group Inc., where he helped Twitter go public. He served as the social-media company’s finance head before taking over as chief operating officer in 2016. Noto has played a leading role in directing the company’s product vision, especially in shaping the platform’s future around live video streaming.

"He has been reassuring force for investors even amidst the stock’s volatile performance over the past several years," Anthony DiClemente, an analyst at Evercore ISI, wrote in a note. "Investors may not ascribe similar confidence in a replacement lacking the unique combination of established track record within Twitter as previous Wall Street experience."

Twitter fell as much as 3.9 per cent to US$22.41, the biggest intraday drop since Nov. 29.

Noto comes into the role at closely held SoFi facing a number of questions, including the direction of the online lending firm. San Francisco-based SoFi, one of the most valuable fin-tech startups, lost its co-founder and CEO, Mike Cagney, last fall amid company turmoil, including allegations of sexual harassment and fraudulent actions by managers. Other high-ranking executives have also departed, leaving it without a permanent chief financial officer and chief revenue officer.

Cagney had envisioned building SoFi into a bank of the future, targeting millennial consumers with products ranging from insurance and mortgages to wealth management. With Cagney gone, those plans have been slowed or put on hold.

SoFi Executive Chairman Tom Hutton has served as interim CEO since Cagney stepped down. He will become non-executive chairman of the board.

Noto’s responsibilities for Twitter’s business operations and revenue-generating operations will be assumed by other members of the company’s leadership team, it said. Matt Derella, Twitter’s vice president of global revenue and operations, will continue to lead the company’s advertising sales efforts.