Wall Street stocks tumbled on Friday, concluding the week on a sour note as a big drop in Treasury yields underscored worries about an economic slowdown.

Analysts said recent data points, including lackluster US retail sales data and a tepid forecast from Walmart, raised questions about the outlook of the US economy as President Donald Trump presses on with tariffs and government job cuts that could boost unemployment.

"You are starting to see some disappointment in the economic data," said Tom Cahill of Ventura Wealth Management, who tied Friday's big drop in the 10-year US Treasury note yield to economic worries.

The Dow Jones Industrial Average finished at 43,428, down 1.7 percent to around 750 points.

The broad-based S&P 500 also dropped 1.7 percent to 6,013, while the tech-rich Nasdaq Composite Index fell 2.2 percent to 19,524.

On Friday, an S&P Global reading on US services industry activity fell to a 25-month low, while a University of Michigan survey of consumer sentiment tumbled nearly 10 percent from January.

LBBW's Karl Haeling said both are considered "secondary" economic reports, but they corroborate other major data points on employment and retail sales that have also pointed to weakness.

"Investors ever since the election have been very bullish," he said, pointing to "all the uncertainty coming from Trump."

Of the 11 sectors in the S&P 500, only consumer staples finished in positive territory, while technology, industrials, energy and consumer discretionary lost about two percent or more.

A particularly big loser was UnitedHealth Group, which dropped 7.3 percent after the Wall Street Journal reported that the Justice Department is investigating allegations the company directed doctors to make patient diagnoses that would trigger higher government payments under the US Medicare Advantage program. (AFP)