Gains by tech giants Nvidia, Apple and Oracle helped propel US equity indices to fresh records on Monday, overcoming early weakness and concerns the market could be overvalued.

For the third straight session, all three major indices powered to new all-time peaks, led by the Nasdaq, which finished up 0.7 percent at 22,788.

The Dow Jones gained 0.1 percent to 46,381, while the S&P 500 climbed 0.4 percent to 6,693.

After a slow start, the market "started to rebound and we saw a very familiar buy-the-dip trade that was led by the mega cap stocks," said Briefing.com analyst Patrick O'Hare.

"The AI trade kicked in with news about Nvidia's investment in Open AI."

Nvidia gained four percent after the chip company announced it would invest up to US$100 billion in OpenAI, building infrastructure for next-generation artificial intelligence.

Also rising significantly was Oracle, which surged 6.3 percent after announcing that Clay Magouyrk and Mike Sicilia would serve as co-chief executives as the software giant beefs up its AI initiatives. Safra Catz is stepping down as CEO and will transition to executive vice chair.

The changes come as Oracle is poised to provide security for a US version of TikTok's algorithm under an agreement brokered by the Trump administration that a senior White House official said would bring the Chinese-owned app's American operations into a US-based entity.

Apple, meanwhile, jumped 4.3 percent, extending a rally on positive buzz over demand for its new iPhones.

Elsewhere, Pfizer rose 0.1 percent as it announced it will acquire Metsera, a maker of drugs for obesity and heart disease, for US$4.9 billion. Metsera surged 60.8 percent.

This week's calendar includes a speech by Federal Reserve Chair Jerome Powell on Tuesday, as well as key inflation data on Friday. (AFP)