Tech shares suffered another bout of weakness on Wednesday on worries about an AI bubble, hitting US stocks as oil prices advanced following a US announcement of a blockade of tankers to Venezuela.

The Nasdaq led major Wall Street indices lower following reports questioning the financing of an Oracle project to build a data centre in Michigan.

Art Hogan of B Riley Wealth Management described Oracle as "probably the poster child" for questions about AI project financing and profitability.

"Investors are starting to be more differentiated and looking at the potential winners and the potential time frame before return on invested capital," Hogan said. "That doesn't mean we're anywhere close to the final innings of artificial intelligence. It just means investors are being more discerning."

Besides Oracle, which fell 5.4 percent, other AI players such as Nvidia, Google parent Alphabet and Broadcom all lost more than three percent.

While technology and communications services were among the sectors to retreat, energy led the winners among sectors moving higher.

Oil prices rallied after US President Donald Trump ordered a blockade of "sanctioned" oil tankers heading to and leaving Venezuela.

The commodity later pared some of its gains, but finished the day up more than one percent.

Venezuela, which has the world's largest proven oil reserves, shrugged off the threat of more pain, insisting that it was proceeding with business as usual.

"Export operations for crude and by-products continue normally. Oil tankers linked to PDVSA operations continue to sail with full security," state oil company Petroleos de Venezuela (PDVSA) said.

Shares in Netflix climbed 0.2 percent after Warner Bros Discovery rejected a hostile takeover bid by Paramount in favour of being acquired by the streaming giant.

Shares in Warner Bros Discovery shed 2.4 percent and shares in Paramount tumbled 5.4 percent.

The S&P 500 fell 1.2 percent, for its worst day in nearly a month, to 6,721, the Dow fell 0.5 percent, to 47,885, and the Nasdaq fell 1.8 percent, to 22,693. (AFP)