The US markets turned negative as investors continue to cautious about Greece's ability to meet its debt obligations.
The Dow Jones Industrial Average was down 143.57 points, or 1.35%, at 10,511.73. The Standard & Poor's 500 Index was down 9 points, or 0.83%, at 1,090.16. The Nasdaq Composite Index was up 0.72 points, or 0.03%, at 2,335.11.
In earlier trading session, the overall stock market trimmed losses on comments from Federal Reserve Chairman Ben Bernanke that he was ready to take more steps to help the fragile recovery.
