U.S. stocks got a boost Thursday as investors listened to testimony from Federal Reserve (Fed) Chair Janet Yellen and dug into the earnings of some troubled retailers. In U.S. economic news, Yellen testified before the Senate Banking Committee. She blamed recent lackluster economic data on unusually bad weather, but said it is difficult to pinpoint exactly what effect the weather had on the economy overall. In international economic news, investors were keeping a close eye on the tension in Ukraine. European markets finished the day mixed as traders fretted about the formation of a new Ukrainian government and its increasingly dire economic situation. Asian markets also ended with mixed results. In corporate news, shares of J.C. Penney surged more than 25 percent after the retailer reported a narrower-than-expected quarterly loss and said it expects same-store sales to rise by 3 percent to 5 percent during the current quarter. Best Buy shares ended in the red after initially jumping by more than 5 percent. The electronics retailer reported quarterly earnings that had returned to profit from earlier losses. Tesla shares initially got a boost after the automaker announced it was raising $1.6 billion to fund its expansion plans. But shares pulled back and finished the day slightly lower. Shares of eBay rose after Carl Icahn issued a letter criticizing the two members of the internet commerce giant's board of directors for alleged conflicts of interest. It was the activist investor's second letter on the subject this week. The dollar lost ground against the pound, but gained ground versus the euro and the yen. Light sweet crude oil for April delivery dropped 19 cents to $102.40 a barrel on the New York Mercantile Exchange. Gold futures added $3.80 to $1,331.80 an ounce. The Dow Jones industrial average climbed 74.24, or 0.46 percent, to 16,272.65. The broader Standard & Poor's 500 index moved up 9.13, or 0.49 percent, to 1,854.29. The technology-heavy Nasdaq composite index rose 26.87, or 0.63 percent, to 4,318.93.