For the first time since May, the major US stock indexes also closed out the month in the red, after bruising weeks when trade war and economic fears eroded gains won in June and July.

Key indexes posted a split finish, with the benchmark Dow Jones Industrial Average sprinting into positive territory in the final moments of the trading day, closing up 0.2 percent at 26,403.28.

But the broader S&P 500 ended essentially flat, up less than a tenth of a percent at 2,926.46, while the tech-heavy Nasdaq fell 0.1 percent to close out the month at 7,962.88.

Tom Cahill of Ventura Wealth Management told AFP stocks had fallen from their session highs as traders exercised caution or cashed in after the gains scored during the week.

"It's profit taking after a pretty nice few days," he said. "If you're a trader and have pretty good profits, it would be a good time to take some off the table."

He also noted that the S&5 500 tended to "run out of steam" as it approached the 2,940 mark.

US markets will be closed Monday for the Labor Day holiday, which falls a day after President Donald Trump is due to jack up import duties on more than $100 billion in Chinese imports, escalating his trade war with China.

"There's a little bit of caution here," Cahill said.

Wall Street got a dose of mixed economic news early in the session, with consumer spending up a better-than-expected 0.6 percent in July but an important consumer confidence index taking its biggest tumble since 2012 as trade war fears filter through to the public.

Trump also lashed out of at "badly run and weak companies," saying they were blaming their problems on the tariffs.

The past week drew another batch of corporate earnings which warned the tariffs were a threat to profits, a sentiment echoed by multiple industries.

Among individual companies, Campbell Soup Co jumped 3.9 percent after posting better-than expected quarterly earnings.