At last check, Fitbit shares were 1.4% lower. They closed the regular session Thursday off 0.5% at $6.44.
The GAAP net loss was 46 cents a share in the quarter, compared with profit of 6 cents in the year-earlier quarter. The adjusted loss in the latest quarter was 12 cents a share. Revenue fell to $502.1 million from $571.2 million.
Analysts surveyed by FactSet were expecting the company to report adjusted earnings of 4 cents a share on revenue of $531.7 million.
The company reported selling 16 million devices and its smartwatch segment grew 45% at retail thanks to demand for its newer device, Versa 2.
The company also launched its premium membership service for interactive exercising, which it called its "most personalized experience yet."
The new service is "seeing improving retention and engagement due to its actionable guidance and coaching," Chief Executive James Park said in a statement.
"Looking ahead, we expect to grow our higher-margin revenue streams in 2020,”
In 2020 through the regular session Thursday, Fitbit stock was off 2%. The stock had more than doubled over the past six months after reaching an all-time low in August.
That merger is under scrutiny from the EU, which is worried about privacy risks.
"The possible further combination and accumulation of sensitive personal data regarding people in Europe by a major tech company could entail a high level of risk to privacy and data protection," the European Data Protection Board had said in a statement.