“It is rich (in valuation) as of now and if prices and earnings continue to converge, I wouldn’t be concerned.”
Among sectors, the technology index has been the best performer, rising about 37 percent and outpacing gains in the broader S&P index.
Telecom services and energy are the only two sectors to end the year in the red.
The rally is widely expected to extend into 2018, boosted by gains from a new law that lowers the tax burden on U.S. corporations.
At 12:19 p.m. ET (1719 GMT), the Dow Jones Industrial Average was down 14.16 points, or 0.06 percent, at 24,823.35 and the S&P 500 was down 1.79 points, or 0.06 percent, at 2,685.75.
The Nasdaq Composite was down 10.92 points, or 0.16 percent, at 6,939.24.
Apple declined 0.52 percent after issuing a rare apology for slowing older iPhones with flagging batteries.
Goldman Sachs lost 0.5 percent after saying its fourth-quarter profit would take a $5 billion hit related to the new tax law.
Trading volumes remained light in the holiday week ahead of New Year.
The consumer staples index was the only major gainer, with a 0.5 percent rise.
Altria, Coca-Cola and Philip Morris, gained between 0.9 percent and 1.5 percent.
Amazon slipped 0.6 percent after President Donald Trump targeted the online retailer in a call for the country’s postal service to raise prices of shipments in order to recoup costs.
Advancing issues outnumbered decliners on the NYSE by 1,479 to 1,325. On the Nasdaq, 1,510 issues fell and 1,360 advanced.
(Reporting by Sruthi Shankar in Bengaluru; Editing by Anil D’Silva)