Social Finance, a privately held online lender and technology start-up, said on Friday that Mike Cagney would step down immediately as chief executive, accelerating a departure announced this week amid a sexual harassment scandal.

The board of the company, which is based in San Francisco and known as SoFi, said that Tom Hutton, the executive chairman, would be the interim chief executive and would take over day-to-day management responsibilities. Mr. Hutton, an initial SoFi investor, has been on the SoFi board since 2012.

“The business is strong, stable and well-positioned,” Mr. Hutton said in a statement. “For now, there is no more important work than paving the way for future success by building a transparent, respectful and accountable culture.”

Mr. Cagney, 46, said in a letter on Monday that he would leave his position at the end of the year amid a sexual harassment lawsuit, accusations that he had inappropriate relationships with company employees and questions about whether he had skirted risk and compliance controls.