* Pfizer to buy Hospira for about $15 billion
* Michael Kors tumbles after results, outlook
* Crude climbs to push energy shares higher
* Indexes up: Dow 0.9 pct, S&P 0.8 pct, Nasdaq 0.6 pct (Updates to afternoon)
By Caroline Valetkevitch
NEW YORK, Feb 5 (Reuters) - U.S. stocks climbed on Thursday as energy shares bounced with oil prices, while news Pfizer would buy Hospira in a massive deal also lifted boosted sentiment.
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.
Oil prices bounced from the prior session's selloff, with U.S. crude rising 4.2 percent to settle at $50.48. The S&P energy index jumped 1.3 percent.
The combination of M&A news and a rebound in oil prices is helping the market, said Peter Cardillo, chief market economist at Rockwell Global Capital in New York. "Anytime you have M&A, it's positive for the market," he said, because it's a sign that there's further economic growth ahead.
Pfizer 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 35.1 percent to $87.56 as the best performer on the S&P 500, while Pfizer gained 1.9 percent $32.69 as one of the biggest boosts to the index.
At 2:32 p.m., the Dow Jones industrial average rose 166.46 points, or 0.94 percent, to 17,839.48, the S&P 500 gained 16.37 points, or 0.8 percent, to 2,057.88 and the Nasdaq Composite added 35.44 points, or 0.75 percent, to 4,752.14.
The S&P 500 has been volatile recently due to swings in crude prices and developments in Greek debt negotiations. Greece said on Thursday it would not be "blackmailed" by its European Union partners but it wanted to find a joint solution to its debt and austerity crisis.
Other data showed the U.S. trade deficit in December widened to its highest since 2012, which could damp down the fourth-quarter growth estimate, and nonfarm productivity fell more than expected in the fourth quarter.
Michael Kors shares fell 3 percent to $69.26 after the luxury accessories retailer posted third-quarter results and forecast a lower-than-expected profit for the current quarter.
Advancing issues outnumbered declining ones on the NYSE by 2,229 to 800, for a 2.79-to-1 ratio; on the Nasdaq, 1,963 issues rose and 744 fell, for a 2.64-to-1 ratio favoring advancers.
The S&P 500 was posting 40 new 52-week highs and 2 new lows; the Nasdaq Composite was recording 82 new highs and 32 new lows. (Editing by Bernadette Baum and Nick Zieminski)