Stitch Fix shares continued to sell off Tuesday, as investors worried about the subscription-based styling service's ability to keep growing its base of active users.

Late Monday, the company reported fiscal first-quarter earnings and sales that topped analysts' expectations. But a 22 percent gain in the number of active users on its platform during that period disappointed Wall Street. Active clients — those people who received a box of clothing in the preceding 12-month period — grew to 2.9 million, slightly below the 2.95 million analysts were predicting. In the previous quarter, Stitch Fix also struggled to meet active users expectations, as many people are seen trying the service but not remaining members.

In the second and current quarter, the company added it anticipates its number of active clients to stay relatively flat compared with the first quarter, while revenue per user is forecast to be up.

Following the news Monday, Stitch Fix shares initially surged as much as 11 percent on the earnings beat but then pared those gains as investors dug into the numbers. The stock was down nearly 25 percent in trading Tuesday morning, shaving off roughly $684 million in market cap from the company, which is valued at $1.9 billion. Ahead of the earnings report, Stitch Fix shares had gained nearly 3 percent so far this year.

Having just gone public one year ago, Stitch Fix has been looking for ways to diversify its sources of revenue while managing investments. It said it benefited during the latest quarter from adding new brands like Michael Kors, Bonobos, Converse and Madewell for shoppers to receive items from. In the men's category, it added expanded sizes for clothes up to 3XL. It also continues to add more options for plus-size women. And the first quarter was the company's first full quarter selling items for kids.

Stitch Fix reported quarterly net income of $10.7 million, or 10 cents a share, compared with $1.3 million, or 4 cents per share, a year ago. Analysts were calling for earnings of 3 cents per share, based on a poll by Refinitiv.

Sales during the first quarter grew 24 percent to $366 million, better than the $358 million expected by analysts.

"All of our assortment investments are deeply rooted in direct feedback from clients, so we're confident they're going to love our new additions," President and COO Mike Smith said in a statement.

The company said it's now expecting second-quarter revenue to fall between $360 million and $368 million, compared with analysts' expectations for $362 million.