Declines in the communications services group, led by Facebook, pushed the S&P 500 down 0.1 percent to 2,808.48. Facebook shares also weighed on the Nasdaq, which closed down 0.2 percent at 7,630.91. The Dow Jones Industrial Average, meanwhile, eked out a 7.05-point gain to close at 25,709.94.
Facebook shares slid 1.9 percent after a worldwide outage of its core app, Instagram and WhatsApp. The social media company's stock was also under pressure after The New York Times reported federal prosecutors are conducting a criminal investigation into data deals the company made with other tech giants.
New home sales fell 6.9 percent in January — which was more than expected and a sign the U.S. government shutdown could have kept buyers on the sidelines.
Investors also grappled with ongoing trade negotiations between China and the U.S. CNBC learned through three sources briefed on the matter that China wants to link a formal state visit to the U.S. to a trade-deal announcement. The sources said China wants a deal to be fully ironed out before Chinese President Xi Jinping sat down with President Donald Trump. They also said, however, Trump prefers to close the deal himself with Xi in person.
Bloomberg News reported earlier in the day that China and the U.S. are trying to push back a meeting between the countries' two leaders from late March to April at the earliest. This comes after Trump said he was in no rush to form an agreement. Bloomberg's report comes after China's industrial output expanded at its slowest rate in 17 years.
Investors expected the two leaders to meet at Mar-a-Lago later this month as both sides claimed progress was being made on trade negotiations.
Bryan R. Smith | AFP | Getty Images
Apple shares rose more than 1 percent after Cowen initiated coverage of the company with an outperform rating and a $220 price target. Cowen cited potential long-term upside from Apple's services business.
Snap, meanwhile, rallied more than 12 percent after BTIG analyst Richard Greenfield — a longtime skeptic of the social media company — upgraded the stock to buy for the first time. "Performance advertisers are laser focused on return on investment and spend (and spend more) where they see a compelling return," he said, noting the stock could rise 50 percent in the next 12 months.
The S&P 500 tech sector has been on fire this week, rallying more than 3 percent through Thursday's close. It is also the best-performing sector year to date.
"This is a move to the upside after such dramatic move to the downside in late December," said Jeff Zipper, managing director of investments at U.S. Bank Private Wealth Management. "Valuations are to the point where they're not extended, so technology is an area we still like."
Elsewhere, General Electric seesawed after the industrial giant issued weaker-than-expected earnings guidance for 2019. The stock initially fell around 4 percent in the premarket before turning around to close 2.8 percent higher.
—CNBC's Sam Meredith and Michael Sheetz contributed to this report.