There is a growing sense that the US stock market's rally from the lows of March 2009 has run out of momentum.

In the coming week, the market could face more turbulence, with doubts racing through the global community about the pace of the global recovery.

Europe's sovereign debt is also rattling investors, with fears about the stability of governments that stand behind the euro.

There has been extreme worry in financial circles in the past weeks about the fiscal upheaval in Greece, Portugal and Spain.

As a result, the euro has fallen sharply against the US dollar, hurting stocks and the prices of global commodities.

On Friday, the benchmark S&P 500 capped its fourth straight weekly decline, falling 0.7 percent.

The Dow dropped 0.6 percent and the Nasdaq shed 0.3 percent.