Wall Street equities closed mostly lower on Tuesday as investors waited with bated breath for Fed Chair Jerome Powell's end-of-week speech and any revelations on his interest rate plans.

Powell is due to appear at the annual gathering of central bankers in Jackson Hole, Wyoming on Friday, and expected to reiterate the message that the Fed is not yet ready to end the steep rate hikes needed to quell the surge in inflation, despite some signs of progress.

"I think that investors are bracing for some hawkish commentary from Fed chair Powell this coming week," said Jack Ablin of Cresset Capital.

Meanwhile, the latest data on new home sales, showed a sharp decline in July to their lowest rate since early 2016, as the real estate market continues to feel the impact of higher borrowing costs.

The week also will feature a key report on the Fed's favoured inflation index, as well as consumer confidence, sales of big-ticket goods and an updated read on second quarter GDP, which fell 0.9 percent.

The Dow Jones Industrial Average lost 0.5 percent to finish the day at 32,909.59.

The broad-based S&P 500 slipped 0.2 percent to 4,128.73, while the tech-rich Nasdaq Composite Index was flat, closing at 12,381.30.

Among individual stocks, Twitter dropped 7.3 percent after the social media platform's former security chief claimed in whistleblower testimony that it misled users and US regulators about gaps in its online protections.

And pandemic darling Zoom Video fell 16.5 percent after second-quarter results revealed a slowdown in revenue growth. (AFP)