Why Ambarella Inc., Bitauto Hldg Ltd, and FireEye Inc. Soared Today

Although we don't believe in timing the market or panicking over daily movements, we do like to keep an eye on market changes -- just in case they're material to our investing thesis.

Santa Claus delivered the much-anticipated rally on the day after the Christmas holiday, as investors were heartened by early estimates that the holiday season went better than some had expected. Even as 10-year bond yields hit the 3% level, experts saw the move as simply stressing the importance of moving more money into stocks. Among the day's biggest gainers, Ambarella , Bitauto Holdings , and FireEye showed up near the top of the list.

Ambarella gained 6% as the chipmaker continued its upward run from late last week, when the high-definition video-chip maker announced a deal with Google to work on a wearable camera. Both companies expect to show off their proposed design at the Consumer Electronics Show in Las Vegas early next month, and Google hopes to use the camera in conjunction with its Helpouts service to connect instructors to students via live video in order to provide training and other interactive learning. Given Google's recent gains, tying up with the online search giant is a smart choice for Ambarella.

Bitauto climbed almost 8% as the Chinese auto-website operator attracted investors looking to cash in on China's rising middle class. As more Chinese residents reach the point financially at which they can start looking at buying a car, Bitauto stands to gain if it can bolster its reputation as a source of vehicle information. The company certainly has plenty of competition in the Chinese auto-marketing space, but Bitauto has been on growth investors' radars for months, and could take more than its share of the market if it can use its early mover status to its advantage.

FireEye jumped more than 8%. The maker of malware protection systems has seen its shares bounce up and down since its September IPO, but over the past month, the company has added nearly 30% on enthusiasm over FireEye's ability to support companies trying to use data analytics to make the best use of the information they collect from customers and others. Products like its cloud-based email threat prevention platform are quite timely, given the hacking attack on Target that put 40 million customers' financial information at risk.