NEW YORK (Feb 6): U.S. stocks climbed on Thursday as energy shares bounced with oil prices, while news Pfizer would buy Hospira in a massive deal further boosted the market.

The S&P energy index jumped 1.5 percent as oil prices rebounded sharply from a rout in the previous session. U.S. crude rose 4.2 percent to settle at $50.48 following increased violence in producer Libya and on an expected boost in oil demand from China's central bank easing.

Some euro zone concerns eased as well. Greece proposed a bridging program until the end of May to allow time for debt talks, vowing to do everything in its power to avoid default. On Wednesday, the European Central Bank abruptly said it would stop accepting Greek bonds in return for funds.

"The market's trying to get its hands around what's going on in Greece. There was an expectation it might blow up. Now, certainly in the short term, it looks like we won't be seeing any fireworks," said Brad McMillan, chief investment officer for Commonwealth Financial in Waltham, Mass.

The day's move put the S&P 500 back into positive territory for the year after days of volatile price action, largely driven by moves in oil.

Pfizer was among the biggest boosts to the S&P 500 after it said it would buy Hospira Inc for about $15 billion to boost its portfolio of generic injectable drugs and copies of biotech medicines. Hospira shares rocketed 35.2 percent to $87.64 as the S&P 500's biggest percentage gainer. Pfizer gained 2.9 percent $32.99.

The Dow Jones industrial average rose 211.86 points, or 1.2 percent, to 17,884.88, the S&P 500 gained 21.01 points, or 1.03 percent, to 2,062.52 and the Nasdaq Composite added 48.39 points, or 1.03 percent, to 4,765.10.

Adding to the upbeat tone, weekly jobless claims rose less than expected last week. The report comes on the heels of a private payrolls report that fell short of expectations on Wednesday and ahead of a monthly employment report on Friday.

Other data showed the U.S. trade deficit in December widened to its highest since 2012, which could dampen the fourth-quarter growth estimate, and nonfarm productivity fell more than expected in the fourth quarter.

After the bell, shares of LinkedIn rose 6.5 percent to $253.50 following a bigger-than-expected jump in quarterly revenue, while shares of Twitter were up 7.6 percent at $44.40 also as quarterly revenue surpassed analysts' expectations.

Michael Kors shares fell 2.3 percent to $69.77 after the luxury accessories retailer posted third-quarter results and forecast a lower-than-expected profit for the current quarter.

About 7 billion shares changed hands on U.S. exchanges, below the 8.1 billion average for the last five sessions, according to BATS Global Markets.

NYSE advancing issues outnumbered declining ones 2,349 to 749, for a 3.14-to-1 ratio; on the Nasdaq, 2,028 issues rose and 718 fell, for a 2.82-to-1 ratio favoring advancers.

The S&P 500 posted 43 new 52-week highs and 2 lows; the Nasdaq Composite recorded 90 new highs and 36 lows.