A wow day for the stock market as the Dow jumps 420 points, the biggest point gain since 2011. The S&P had its best day of year, up 2.4%.

After starting the day higher, benchmark U.S. crude resumed its slide by mid-morning. The price of oil dropped 88 cents, or 1.6 percent, to $55.87 after rising as high as $58.71 in morning trading. Oil has plunged since June, when it peaked at $107 a barrel. Overproduction and weak demand are behind the fall in global oil prices. Brent crude, a benchmark for international oil, dropped 64 cents, or 1.1 percent, to $60.51 a barrel.

"The bottom line is that low oil is a net positive for the consumer," Karyn Cavanaugh, a senior market strategist at Voya Investment Management. "The consumer drives the U.S. economy, which drives the global economy, so that's good news."

EARNINGS BEAT: Oracle posted better-than-expected results late Wednesday in its first quarterly report since co-founder Larry Ellison gave up the helm of the business software maker. The company reported that its software and cloud revenue grew 5 percent. The stock rose $3.39, or 8.3 percent, to $44.61.

FED SPARK: Stocks are building on a rally that was driven by steadying oil prices and comments from the Federal Reserve Wednesday after its last policy meeting of the year.

Stocks surged after the Fed said that while it was edging closer to raising interest rates from close to zero, it will be "patient" in deciding when to do so. Fed Chair Janet Yellen said she foresaw no rate hike in the first quarter of 2015.

OIL RESUMES SLIDE: After starting the day higher, benchmark U.S. crude resumed its slide by mid-morning. The price of oil dropped 88 cents, or 1.6 percent, to $55.87 after rising as high as $58.71 in morning trading. Oil has plunged since June, when it peaked at $107 a barrel. Overproduction and weak demand are behind the fall in global oil prices. Brent crude, a benchmark for international oil, dropped 64 cents, or 1.1 percent, to $60.51 a barrel.