A runner wearing a Fitbit.
Source: Fitbit
FitBit shares jumped Monday on a report that the wearable fitness device maker's app scored the No. 1 spot in the App Store for free apps on Christmas Day, according to several media reports.
Shares of FitBit were up nearly 5 percent in premarket trading. (Get the latest quote here.)
Fitbit's iOS app has been at top of Apple's health and fitness charts each day into December, but last Friday marked the first time it was atop free app list, according to a report by StreetInsider.com.
Up to Thursday's close, FitBit's stock had gained nearly 45 percent since its debut on June 18.
— CNBC contributed to this report.