U.S. stocks overcame an afternoon slump to rebound from the lowest level in 21 months, as crude surged toward $30 amid signals from China and Europe that officials will add to stimulus if needed. Treasuries fell with gold as haven demand waned.

The Dow Jones Industrial Average rose 115 points in a seesaw session that had the gauge erase almost all of a 270-point rally before ending higher. Investors piled into risk assets, boosting European equities to the biggest gain in a month and sending crude 4.2 percent higher, after the European Central Bank said it may bolster support as soon as March. China's vice president said the government would intervene to tamp down market volatility. The yield on the 10-year Treasury note rose to 2.02 percent.

ECB President Mario Draghi signaled at his briefing Thursday that additional support is available as soon as March as distress in China shows few signs of abating and oil's slump fuels disinflation. Risks to economic growth have increased amid the financial-market turmoil that has erased more than $15 trillion from global equity values as markets from Japan to Germany and Brazil plunged into bear territory.

Crude's climb above $29 a barrel in New York provided a glimmer of relief to commodities investors battered by an oversupply in resources from oil to copper and wheat. Calling the country's market "not yet mature," China's Vice President Li Yuanchao said the government would boost regulation in an effort to avoid too much volatility. Corporate earnings may also offer clues on the robustness of the U.S. recovery, with the few companies that have reported so far mostly exceeding estimates.

The S&P 500 rose 0.5 percent at 4 p.m. in New York, capping a session that saw it rise as much as 1.6 percent after falling 1.2 percent Wednesday to the lowest since April 2014. The index has swung from gains to losses for seven consecutive sessions as investors seek a bottom to a rout this year that's erased 8.3 percent from the benchmark.

Energy shares paced gains with a 3.1 percent advance. Chevron Corp. climbed 2.6 percent and Home Depot Inc. surged 3.5 percent as energy and consumer discretionary companies paced the rebound from yesterday's selloff. Verizon Communications Inc. gained 3.5 percent after its profit beat estimates. Union Pacific Corp. fell 4.9 percent after its earnings missed forecasts.