In other deals, RF Micro Devices said Monday it agreed to buy TriQuint Semiconductor for about $1.6 billion, while Men's Wearhouse raised its cash tender offer for rival men's clothing retailer Jos. A. Bank Clothiers Inc to $63.50 per share from $57.50.
Humana and UnitedHealth Group were both among the S&P's biggest percentage gainers, with Humana up 8.2 percent to $111.24 after it said the government's proposed cuts to the private Medicare program appeared to be less than it had forecast. UnitedHealth rose 3 percent to $75.99.
Aetna rose 2.4 percent to $72.14 after giving a 2014 earnings outlook.Elsewhere in financial markets, U.S. Treasuries' prices changed little on Monday, with trading in the safe-haven asset class unaffected by political upheaval in Ukraine and mixed readings from big economies such as those of Germany and China.
Investors had scant guidance for trading and will likely wait until at least Thursday, when Federal Reserve chief Janet Yellen appears before Congress, according to DRW Trading strategist Lou Brien in Chicago."We seem to be in a time when we are floating around with the flows," Brien said. "We have Yellen on Thursday and her testimony may be a little different ... and we have some interesting data on Friday."
Markets have mostly shrugged off weaker-than-expected U.S. economic reports because much of the nation was hit by rough winter weather that had slowed business and spending, according to TD Securities analyst Gennadiy Goldberg in New York.
"We largely expect this week's key data releases to be relatively soft," Goldberg said in a commentary. "We nevertheless look for markets to discount a large portion of the data weakness due to ongoing winter weather distortions."
Investors may be stung by likely downward revisions on Friday to fourth-quarter gross domestic product estimates, said Goldberg, who sees Treasury yields grinding higher in coming weeks.