(Bloomberg) -- U.S. stocks swung between gains and losses, after the Standard & Poor’s 500 Index closed near a record, investors awaited testimony from the Federal Reserve’s Janet Yellen and tension increased in Ukraine.

General Motors Co. slipped 1.5% as U.S. regulators said they are investigating why the automaker took years to recall 1.6 million small cars over an ignition-switch defect. Sears Holdings Corp. rose 6% after reporting a narrower fourth-quarter loss. J.C. Penney Co. surged 21% as it predicted an increase in annual revenue and wider margins. Best Buy Co. added 5.4% as profit topped analyst estimates.

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