NEW YORK (AFP) - Wall Street stocks fell sharply on Thursday (July 6) as worries about tightening monetary policy and North Korea's nuclear ambitions weighed on sentiment.

The declines were fairly broad-based, with several sectors down one percent or more including energy, industrials and health. Equity markets in Europe and Asia also retreated and global bond yields advanced in expectations that central banks will soon curtail stimulus efforts.

"There's an overall concern among investors that global central banks are going to begin tightening," said Bill Lynch, director of investment at Hinsdale Associates.

Investors also were uneasy as a Group of 20 (G-20) summit was set to kick off in Germany amid rancorous protests and unease over North Korea. President Donald Trump said the US was weighing a "pretty severe" response to North Korea, while Beijing called for a scaling down of rhetoric.

The Dow Jones Industrial Average dropped 0.7 per cent to close the session at 21,320.18.

The broad-based S&P 500 tumbled 0.9 per cent to end at 2,409.80, while the tech-rich Nasdaq Composite Index fell 1.0 per cent to 6,089.46.

General Electric slumped 3.8 per cent after JPMorgan Chase cut its price target on expectations of weak profit growth from key industrial divisions. "We don't see a quick or easy fix to the current predicament."

Tesla Motors fell sharply for the third straight session, this time losing 5.9 per cent as it ceded its crown as biggest US carmaker by market capitalisation to General Motors. Tesla's failure to garner the top crash test rating added to worries about its profit outlook after it reported lower-than-expected car deliveries earlier this week.

Pharmaceutical shares were laggards, with Bristol-Myers Squibb shedding 1.9 per cent and Mylan and Biogen both losing 2.1 per cent.