U.S. stocks finished deep in the green Tuesday, a day when new Federal Reserve Chairwoman Janet Yellen made her debut on Capitol Hill. Yellen's dovish comments sent the S&P 500 over 1% higher to 1820, while the Dow rose 193 points to 15,995. The tech-heavy Nasdaq finished up 1% at 4,191. In company news, Sprint was up almost 3% after posting a narrower Q4 loss and revenue that exceeded expectations. CVS Caremark finished over 2% higher after beating Q4 earnings expectations by a penny. On the other hand, Rackspace Hosting plunged 19% after the cloud computing company posted exceptionally weak fourth-quarter results and announced the departure of its CEO.