Well, that period of calm didn't last long. After treading water at the start of trading on Thursday, U.S. stocks tumbled over yet more concerns about the European debt crisis, leaving them with another round of substantial losses in midday trading.

At noon, the Dow Jones industrial average was down 71 points or 0.7 per cent, to 10,797. The broader S&P 500 was down 9 points or 0.8 per cent, to 1157.

All 10 subindexes within the S&P 500 were underwater, suggesting a broad-based selloff. However, stocks that are more exposed to the global economy suffered bigger losses.

Financials were the worst hit, falling 2 per cent. Consumer discretionary stocks fell 1.4 per cent, while energy stocks and industrials fell 1.2 per cent each.

Meanwhile, defensive stocks suffered smaller losses. Consumer staples fell 0.4 per cent and health care stocks fell 0.5 per cent.

In Canada, the S&P/TSX composite index was up 18 points or 0.2 per cent, to 11,893 - bolstered, in part, by a string of strong earnings reports before markets opened and a rising gold price.

Financials fell 1.1 per cent and energy stocks fell 1 per cent after the price of crude oil fell below $79 (U.S.) a barrel.

However, the index was supported by gains elsewhere. Consumer discretionary stocks rose 2.5 per cent after Magna International Inc. reported its first quarter results and proposed to end its dual-class share structure.

Materials rose 2.5 per cent after the price of gold jumped $21 an ounce, to nearly $1200.