The S&P 500 failed to break a key technical resistance level for a second day on Tuesday as low trading volume raised further questions about the market's strength.

Trading volume was relatively low with only 7.03 billion shares traded on the New York Stock Exchange, NYSE Amex and Nasdaq, compared with last year's estimated daily average of 8.47 billion.

The Dow Jones industrial average fell 6.13 points or 0.05 per cent to 12,393.90. The Standard & Poor's 500 Index was down 0.24 of a point or 0.02 per cent at 1,332.63. The Nasdaq Composite Index gained 2 points or 0.07 per cent to 2,791.19.

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