The Dow fell while the Nasdaq finished at a fresh record on Thursday as markets grappled with worries over lofty equity valuations in light of President Donald Trump's aggressive trade policies.

After a positive start, momentum on Wall Street faded, with both the Dow and S&P 500 finishing lower.

"This tariff issue is still an overhang for the market as it kind of contemplates what that might mean in terms of inflation, and what it might mean in terms of earnings," said Briefing.com analyst Patrick O'Hare.

"There's concerns about the market acting a little bit too complacent around these tariffs."

The Dow Jones Industrial Average finished down 0.5 percent at 43,968.

The broad-based S&P 500 dipped 0.1 percent to 6,340, while the tech-rich Nasdaq Composite Index gained 0.4 percent to 21,242, a new all-time high.

Tech stocks were lifted by Trump's pledge of chip-tariff exemptions for companies that invest heavily in the United States or commit to do so. The Nasdaq rose 0.4 percent to 21,242, a new all-time high.

Shares in Apple climbed 3.2 percent, adding to a gain of more than five percent on Wednesday when Apple CEO Tim Cook appeared at the White House to pledge new investments in the United States.

Intel dropped 3.1 percent as Trump called on the chipmaker's CEO, Lip-Bu Tan, to resign after a Republican senator raised national security concerns over his links to firms in China.

Eli Lilly plunged 14.2 percent despite reporting a near-doubling of profits on higher revenues.

The drugmaker also released results of clinical testing of a weight loss pill that looked positive "on the surface" but indicated less impact than candidates by other companies, said Briefing.com.

Airbnb dropped 8.0 percent on disappointment over the company's outlook. The vacation rental company described demand as encouraging but warned of weak growth figures later in the year. (AFP)