A late slide in several Big Tech stocks left major indexes lower on Wall Street, even as small-company stocks marched to another record high.
The S&P 500 turned lower in the last hour of trading to wind up with a loss of 0.4% Thursday.
The benchmark index was weighed down by losses in Apple, Microsoft and other huge tech companies.
Small-company stocks continued to rally, a sign that investors are feeling more optimistic about the economy. Treasury yields also rose.
Investors are waiting to hear from President-elect Joe Biden, who's expected to detail his plan bolster the economy in a speech later Thursday.