(Close): Wall Street closed down sharply, joining a global equity sell-off on fears of a Greek debt default.
The Dow Jones tumbled 350.33 points, or 1.95%, to 17,596.35, while the S&P 500 sank 43.85, or 2.09%, to 2,057.64 points. The Nasdaq lost 122.04 points, 2.40%, to 4,958.47.
Greece has shut its banks and imposed capital controls, while Standard & Poor's downgraded Greece's credit rating deeper into junk territory.
Big Dow losers were financial firms.
Visa fell 2.95% and Goldman Sachs was 2.95% lower. No Dow stock ended the day higher.
The losses wiped out all the gains for the Dow and S&P 500 indexes this year.
"There is a lot of nervousness in terms of how all this is going to play out," said Bill Lynch, director of investment at Hinsdale Associates.
The US markets followed losses in Europe, where Germany's Dax lost 3.6%, France's Cac-40 lost 3.7%, and the FTSE 100 fell 2%.
The S&P 500's biggest riser was coal producer Peabody Energy, up 9.61% after the Supreme Court ruled against new rules designed to limit emissions from power stations.
