Shares of Fitbit Inc. are up 1.8% in premarket trading after gaining nearly 15% in Monday's session. The company has seen newfound enthusiasm for its health-solutions business, including from analysts at Citron Research, who made a bullish call on the stock Monday and argued that Fitbit makes an attractive takeover candidate for a company like Alphabet Inc.'s Google. On Tuesday, Fitbit was granted a patent for a "monitoring device using radar and measuring motion with a non-contact device." According to the patent filing, the device would have "one or more microphones, a transmitter and sensors to determine air quality, sound level quality, light quality, ambient temperature and humidity" and communicate with a "cloud-based system." Shares are up 34% so far in June, while the S&P 500 has gained 2.8%.