US stocks Thursday finished mostly higher as concerns about rising tensions in Ukraine cast shadows over largely positive earnings results from Apple and other large companies. The Nasdaq Composite Index jumped 21.37 points (0.52 percent) to 4,148.34. The tech-rich index benefited from a big jump in Apple shares, which rose more than eight percent on earnings that beat Wall Street expectations. The broad-based S&P 500 advanced 3.22 (0.17 percent) to 1,878.61, while the Dow Jones Industrial Average was unchanged at 16,501.65. Brent Schutte, market strategist at BMO Global Asset Management, said investors are worried about Ukraine. On Thursday, Russia ordered new military exercises on the border of Ukraine and warned of "consequences" after Kiev launched a deadly assault against pro-Kremlin rebels occupying a flashpoint town. Investors fear the uncertainty of the Ukraine situation, Schutte said. "You can never say for sure what's going to occur or if it spirals out of control," he said. Apple rose 8.2 percent following a series of shareholder-friendly measures that accompanied earnings that beat expectations by a wide margin. The company unveiled a dividend increase, a ramp-up in stock buybacks and a seven-for-one stock split. Dow component Caterpillar reported earnings of $1.44 per share, 18 cents better than analyst forecasts as improved performance in its energy, transportation and construction sectors made up for continued weakness in the mining sector. The company also boosted its forecast for 2014 earnings. Shares rose 1.8 percent. United Airlines sank 9.8 percent after reporting a loss of $609 million. The company said cancelled flights due to bad winter weather in the US hit earnings by about $200 million. Chief executive Jeff Smisek said the performance was "well below what we can and should achieve." Rival American Airlines reported net income of 54 cents per share, better than the 48 cents projected by Wall Street analysts. Shares rose 0.5 percent. First-quarter earnings at General Motors plunged 85 percent on a $1.3 billion charge for recalling seven million vehicles worldwide. Earnings per share bested Wall Street expectations by two cents at six cents per share. Shares fell 0.6 percent. Bond prices were mixed. The yield on the 10-year US Treasury held steady at 2.69 percent, the same level as Wednesday. The 30-year dipped to 3.46 percent from 3.47 percent. Bond prices and yields move inversely.