Katrina Lake, the founder of the personal styling service Stitch Fix, will step down as CEO of the company, Stitch Fix announced Tuesday.

Lake, who founded the business a decade ago, will become the company's executive chairperson and remain on staff as an employee handling social impact work. Stitch Fix president Elizabeth Spaulding, who joined the company in January 2020, will be its second-ever CEO starting August 1. Stitch Fix stock fell 5% in after-hours trading following the announcement.

"This succession has been in the works for some time, and while change can be hard, I also believe in its transformational power. I am deeply confident in the future ahead for us," Lake wrote in a message to Stitch Fix's workforce of about 8,000 employees and stylists. "I can’t imagine anyone else taking our company forward with such energy, passion, and optimism."

Lake founded Stitch Fix as a personal styling service that sent customers a "fix," or box of clothes to try on, and let them decide what to keep and what to send back. In recent years, the $1.7 billion business has leaned into its technology, relying on its data analytics operation to predict what customers with different preferences and body types are likely to buy or return. The business is now focusing on moving beyond the "fix" to help customers shop in other ways, as Lake described in a recent interview with Fortune.

"There are so many other ways people shop and fixes can be limiting for some of those," Lake said last month. "But those are ones where we can show you recommendations and you can choose from those—that's a more powerful way to shop."

That transition beyond the fix has been a focus of Spaulding's work since she joined the company. "She has defined a compelling vision for our future and accelerated the next generation of our service," Lake wrote to her staff.

Spaulding described that "next generation" of Stitch Fix to Fortune last year as the company launched an initiative allowing non-clients to shop its service. "If you imagine a future for Stitch Fix, it’s one where many clients may want to join for the ‘fix’ experience and then shop, and where others may want to start with the shopping experience without beginning with a fix," Spaulding told Fortune last summer. “This is a foray into that chapter of our future.”

Before she joined Stitch Fix, Spaulding was global head and founder of Bain & Company’s digital practice, where she led work on technology and software development.

Lake's legacy at Stitch Fix includes taking the company public in 2017, which made her the youngest woman to do so until the recent initial public offering for dating app Bumble, led by CEO Whitney Wolfe Herd. In recent months, Lake has led the business through the changing consumer preferences of pandemic and quarantine. In her recent Fortune interview, she described how Stitch Fix's data operation allowed it to adapt more quickly than some retail competitors.

This leadership transition, meanwhile, is a rare example of a female CEO taking over from a female CEO at a public company. (The few examples of such a transition in the Fortune 1000 include a 2012 leadership change at Avon Products and a 2020 switch at Chico's FAS).

"The opportunity that we have ahead of us at Stitch Fix is extraordinary, and grounded in Katrina's vision and last 10 years of building personalization at scale," Spaulding said in a statement on Tuesday. "We are creating experiences that will change the way people shop for generations to come."