Image: Fitbit.

The stock market couldn't carry its positive momentum from last week into the final week of 2015, as investors braced themselves for the possibility of major market benchmarks posting annual losses. The S&P 500 fell below the level where it closed at the end of 2014, as it and the Dow both fell around 0.2%. Yet the gloom, which came largely from another decline in energy prices, didn't hold back every stock in the market. Fitbit (FIT), Rovi (NASDAQ: ROVI), and InterDigital (IDCC 0.20%) were among the winners in Monday's quiet trading.

Fitbit picked up 3% after the maker of fitness-tracking devices got good news in the key holiday session. The company's app topped the charts for the most popular app store on Christmas Day, suggesting that Fitbit devices were a popular gift and were able to fend off potential competition from smart watches and other rival products. Some had feared that even as high-end wearable technology posed a threat to Fitbit's specialty devices, other fitness-centered wearables would eat into Fitbit's lead. The app-store data suggests otherwise, proving that at least for now, Fitbit has differentiated itself successfully from its peers and should be able to capitalize on the fitness trend as New Year's resolution season kicks into high gear.

Rovi soared 12% as the owner of numerous entertainment-industry patents announced that it had successfully renewed a multi-year licensing agreement with consumer electronics giant Sony. The deal gives Sony access to Rovi technology related to media management and television guide services, which helps the devices that Sony makes allow users to access and manage the entertainment of their choice. The question, though, is whether Rovi's deal with Sony will actually lead to improved revenue and earnings to justify the share-price jump, as past deals with cable television giants haven't ended up producing the business gains that investors had hoped to see. Even with those doubts, Rovi has doubled since late October as the company has inked similar deals with other licensing partners.

Finally, InterDigital rose 4% as the mobile-technology company announced a new licensing agreement with handset-maker Kyocera. The deal covers certain cellular terminal unit products and should put Kyocera in a better position to compete with its mobile peers, and InterDigital executive Lawrence Shay said that the agreement "highlights the strength of InterDigital's research and intellectual Property portfolio." InterDigital also gave an update to its fourth-quarter guidance, predicting sales of between $107 million and $111 million, of which about 85% will come from renewing revenue sources. Although the guidance reflects the Kyocera deal and other licensing agreements signed before the day, InterDigital held out the possibility of future agreements that could boost results further.