NEW YORK (AFP) - Wall Street tumbled a fourth straight day on Tuesday as mounting worries over Britain's coming Brexit vote hit especially shares of big banks.

American Express lost 4.1 per cent and Citigroup 2.8 per cent, with the sector under pressure from low interest rates.

Earlier, the yield on one of Europe's safest sovereign bonds, the 10-year German bund, fell below zero for the first time, reflecting broad worries over the global economy and a possible British referendum vote against EU membership on June 23.

"That's really a flight to safety in front of what could be a destabilising event if the vote goes to leave the EU," said Art Hogan of Wunderlich Securities.

The Dow Jones Industrial Average finished down 0.3 per cent at 17,674.82.

The broad-based S&P 500 fell 0.2 per cent to 2,075.32, while the tech-heavy Nasdaq Composite lost 0.1 per cent to 4,843.55.

Trade remained cautious ahead of Wednesday's new policy outlook from the Federal Reserve. With the Fed not expected to increase interest rates, the main issue is how dovish their statement is amid worry over soft jobs data and weak inflation.

Tech stocks were buoyed by a 5.6 per cent jump in Twitter, with Microsoft's deal to buy LinkedIn raising speculation that the micro-blogging service could also be a takeover target.

Chinese online marketplace Alibaba gained 3.1 per cent after it forecast a 48 per cent jump in revenue this year.