The S&P fell 0.1% to 2,347.2, with TripAdvisor down 11% on weak profit figures. But the Dow Jones eked out a tiny gain of 7.9 points to 20,619.7.
The tech-heavy Nasdaq also slid 0.1%, to 5,814.9 points.
After Wall Street's recent strong run, Nate Thooft, of Manulife Asset Management, said the markets were taking "a little bit of a breather".
Signs of a strengthening economy and promises by President Donald Trump to cut corporate taxes and reduce financial red tape have been behind much of the recent gains.
But with a strong fourth-quarter earnings season mostly complete, many investors say they need concrete signs of progress from Trump to justify more gains.
Cisco Systems rose 2.38% after posting quarterly profit figures. Wells Fargo slipped 0.73% after Credit Suisse downgraded its stock to "neutral" from "outperform".
The S&P 500 index ended lower, breaking a seven-day winning streak not seen for three-and-a-half years.