The S&P 500 concluded a strong holiday-shortened week by setting a record Thursday, extending a rally amid optimism that the latest COVID-19 strain will not significantly weigh on growth. 

The broad-based index piled on 0.6 percent to finish at 4,725.79, overtaking a previous record set earlier this month and ending with 2.3 percent for the week. 

The Dow Jones Industrial Average climbed 0.5 percent to close at 35,950.56, while the tech-rich Nasdaq Composite Index jumped 0.8 percent to 15,653.37. 

The session capped a banner three-day run for the market as investors greeted health studies suggesting the Omicron variant of COVID-19, while highly contagious, is less deadly than earlier strains.  

Markets also cheered news U.S. authorities approved new pills to treat the virus developed by Pfizer and Merck. 

"We think there's a lot more optimism around the containment of the pandemic in these last couple of days," said Greg Bassuk, chief executive of AXS Investments. 

A trove of economic data painted a mostly decent picture of the U.S. economy. 

Commerce Department data showed higher consumer spending in November, while inflation posted the biggest increase in nearly four decades. 

The hot housing market also continued to see price pressures amid a shortage of new homes available for buyers, while jobless benefit claims held steady from the prior week and orders for big-ticket manufactured goods climbed, though mostly due to aircraft.