Jack Dorsey's Square Loses Its CFO

Sarah Friar, chief financial officer of Square Inc., speaking during an interview in  2017.

Sarah Friar, chief financial officer of Square Inc., speaking during an interview in 2017.


David Paul Morris/Bloomberg News

Jack Dorsey’s Square Inc. said Wednesday that Chief Financial Officer Sarah Friar is leaving the financial-technology company to become chief executive at neighborhood social network Nextdoor.

Shares were down more than 10% in aftermarket trading following the announcement of Ms. Friar’s departure. They had already fallen more than 10% on Wednesday before market close on a down day for the broader market.

Ms. Friar will remain in her current position into December, the company added. The search for her successor will be led by David Viniar, a Square board member and the former finance chief of

Goldman Sachs Group

A former Goldman Sachs research analyst and


executive, Ms. Friar joined Square in 2012 when the company was best known for its white credit-card readers that plugged into smartphones. She guided Square through a rocky initial public offering in 2015 and served as the face of Square to Wall Street, an important role given that Mr. Dorsey also runs another public company,


Ms. Friar also played an instrumental role in Square’s expansion into financial services, from lending to small businesses to letting consumers buy and sell bitcoin through Cash App, Square’s money-transfer service. In recent years, she took additional responsibilities outside Square, including joining the boards of


and Slack Technologies Inc.

Mr. Dorsey said in a note to employees that it was always Ms. Friar’s ambition to serve as a CEO and that Square’s goal is to “build an organization that is not dependent upon any one person, including me.”

“This is an important milestone towards that goal,” he added.

Nextdoor operates private social networks tailored to specific neighborhoods across the country, providing a platform for members to share everything from local-news articles to referrals on babysitters.

As she transitions to her new job, Mr. Friar will have to get used to a much smaller organization. Square has more than 2,000 employees and a market value of over $30 billion. Nextdoor has 225 full-time workers and is a private company.

Nextdoor Chairman Nirav Tolia said in a blog post that Ms. Friar was “one of the most highly regarded executives in Silicon Valley.” Mr. Tolia had served as Nextdoor’s CEO until this summer.

Write to Peter Rudegeair at Peter.Rudegeair@wsj.com