1,502.32. The Nasdaq Composite Index was up 6.99 points, or 0.22 percent, at 3,149.29.
The S&P 500 has advanced more than 5 percent in January after legislators in Washington temporarily sidestepped a "fiscal cliff" of automatic tax increases and spending cuts that could have derailed the recovery. Better-than-expected corporate earnings have added to the gains.
It would be the benchmark's largest monthly advance since a more than 6 percent gain in October 2011 and the best January advance since a 6.1 percent jump in 1997.
UPS shares lost 2.1 percent to $79.50 after reporting fourth-quarter earnings that were below analysts' estimates on Thursday and forecasting weaker-than-expected profit for 2013.
Constellation Brands shares tumbled 16.4 percent to $32.72 after the U.S. Justice Department moved to stop Anheuser-Busch InBev from buying the half of Mexican brewer Grupo Modelo that it does not already own. Constellation would have distributed Corona beer in the United States if the transaction had been approved.
Tank barge operator Kirby Corp added 6.3 percent to $70.67 and transportation company Ryder Systems climbed 4.8 percent to $56.84 after posting quarterly results.
Thomson Reuters data through Thursday morning shows that of the 231 companies in the S&P 500 that have reported earnings this season, 69.3 percent have exceeded expectations, a higher proportion than over the past four quarters and above the average since 1994.
Overall, S&P 500 fourth-quarter earnings are forecast to have risen 3.7 percent. That's above a 1.9 percent forecast at the start of the earnings season but well below a 9.9 percent profit growth forecast on Oct. 1, the data showed.
Slot machine maker WMS Industries surged 51.7 percent to $24.84 after the company agreed to be acquired by Scientific Games for $26 per share in cash. Scientific Games jumped 5 percent to $9.38.