Wall Street stocks fell decisively for a second straight session on Friday following a major IT outage that roiled many businesses at a time when analysts consider the market "overbought."

Airlines, banks, TV stations and financial institutions were among those thrown into turmoil due to a faulty update to an antivirus programme for Windows systems from American cybersecurity group CrowdStrike.

The outage added more uncertainty at a time when markets were already edgy over speculation that President Joe Biden will withdraw from the 2024 campaign.

The Dow Jones finished down 0.9 percent at 40,287.

The S&P 500 dropped 0.7 percent to 5,505, while the Nasdaq declined 0.8 percent to 17,726.

"The market was extremely overbought so it was just a matter of time before we had a pullback," said Tom Cahill of Ventura Wealth Management.

"So far it has been relatively mild and I think earnings are going to be an important factor as to whether" the market keeps falling, Cahill said.

Among individual companies, Netflix fell 1.5 percent despite adding eight million new subscribers in the second quarter. But some analysts said the company's third-quarter revenue forecast was disappointing.

Among other companies reporting results, Travelers sank 7.7 percent, while American Express fell 2.7 percent and Schlumberger advanced 2.0 percent.

CrowdStrike, the cybersecurity company at the heart of the global outage, tumbled 11.1 percent. CEO George Kurtz announced that a fix had been rolled out for the problem.

Starbucks jumped 6.9 percent following a Wall Street Journal report that activist investor Elliott Investment Management had taken a stake in the coffee company. (AFP)