The broad index fell 0.3 percent to 2,712.97 with energy and financials lagging. The Nasdaq composite declined 0.4 percent to 7,354.34. The Dow Jones industrial average bucked the negative trend, closing just above the flatline at 24,715.09 as Boeing and Caterpillar shares rose 2.1 percent and 1.3 percent, respectively.
"All of the news we're getting on trade is incremental, unfortunately," said Art Hogan, chief market strategist at B. Riley FBR. "Unless you're in the room, it's hard to get a feel for how these negotiations are going."
On Thursday, the two largest economies in the world began the second round of trade talks. But President Donald Trump told reporters he doubted the negotiations would be successful.
Later, reports emerged saying China would offer the U.S. a $200 billion trade surplus cut. Those reports, however, were quickly denied by a Chinese ministry spokesman on Friday. "This rumor is not true. This I can confirm to you," the spokesman said. "As I understand, the relevant consultations are ongoing and they are constructive."