Wall Street stocks powered higher on Thursday, with the S&P 500 finishing at a fresh record, following strong Micron earnings and statements from Beijing signalling likely additional stimulus.

Analysts described Micron's earnings as a boon not only because they showed strong profitability, but because the company cited "robust" artificial intelligence demand, lifting other tech shares.

Micron itself jumped nearly 15 percent.

The S&P 500 finished up 0.4 percent at 5,745.37, up about 13 points from Tuesday's record close.

The Dow Jones Industrial Average gained 0.6 percent to 42,175.11, narrowly missing a record of its own, while the Nasdaq Composite Index climbed 0.6 percent to 18,190.29.

Market watchers also pointed to statements from President Xi Jinping signaling Beijing's intent to take further steps to boost its economy, following a raft of measures announced earlier this week.

Briefing.com analyst Patrick O'Hare also cited benign US jobless claims data, which adds to confidence the US economy can avoid a recession.

But O'Hare said investors are voicing more worry over excessive valuations, adding, "additional upside from here will feel harder to achieve."

Among individual companies, Southwest Airlines shares gained 5.4 percent after announcing a US$2.5 billion share repurchase program while raising its third-quarter revenue forecast. (AFP)