US stocks finished higher on Wednesday, propelled by resurgent optimism about AI, and fading concern about the economic threat posed by US President Donald Trump's tariffs.

The Dow Jones rose 0.7 percent to 44,873, while the S&P 500 climbed 0.4 percent to close at 6,061.

The Nasdaq edged up 0.2 percent to 19,692, held down by a 7.3 percent fall in the share price of Google's parent company Alphabet following disappointing quarterly results.

There was some good news for companies linked to the artificial intelligence revolution, after Alphabet's pledge to invest US$75 billion in capital expenditure related to AI.

"The market has kind of separated out the weakness seen in Alphabet as sort of just an Alphabet issue," said Briefing.com's Patrick O'Hare.

"You take that big CapEx number and that's a little bit staggering, obviously," he said.

"If they're going to spend 75 billion dollars in 2025, that should be pretty good for, you know, a company like Nvidia," he added, referring to the major chip designer whose shares closed up 5.4 percent.

The move had "helped energise the AI trade a bit," he added. (AFP)