Snap shares plunged 14% on Thursday after the social media firm reported more than $400m (£310m) in quarterly losses and fewer than expected users.
The share price fall extended a decline that started almost immediately after Snapchat started trading on the stock market this spring.
The firm reported 173 million daily users, up 4% on the prior quarter. But the company is struggling with fierce competition from Facebook, which offers similar features.
On Thursday, Chief Executive Evan Spiegel pledged that he and fellow co-founder Robert Murphy would not sell any of their own shares this year, as a sign of confidence in the firm’s prospects.
“We believe deeply in the long-term success of Snap,” he told analysts on a call after the results were released.
Snap made its name as a messaging app, with texts that would disappear. It now offers video stories, maps and other features.
The firm said it is working to woo advertisers with low prices and evidence that its ads are working – features it hopes will set it apart from rivals.
Mr Spiegel said the company was making “a lot of progress”.