Fitbit’s membership base grew 10% last year to 25.4 million users. The company sold 5.4 million devices in Q4 and 15.3 million devices in full year 2017. However, Fitbit’s main market is the U.S., where earnings fell 13.4% to $330.2 million. Analysts were hoping for a break-even quarter, but Fitbit lost $45.5 million. Fitbit believes it will show $1.5 billion in revenue for full year 2018, well below analyst expectations of $1.73 billion.