Credit Suisse expects the S&P 500 index to trade in the 1,100 to 1,300 range, saying that most important potential source of turbulence in equity markets may be the actions of monetary policymakers.

We believe after a couple of months of great flying conditions for US equities, it may get bumpy for a while. We still expect the S&P 500 to trade in the 1,100-to- 1,300 range, but the index could be stuck in the lower half of that range for a while, analyst D. Cliggott wrote in a note to clients.

Cliggot said policy makers are moving in opposite directions due to the heterogeneity of the cyclical positions of big economies. The most important cyclical divergence appears to be the path of consumer prices in China and in the United States, the analyst said.

The People's Bank of China moves to increase reserve requirements for Chinese banks and the associated reduction in available credit to the private sector is a vector working in exactly the opposite direction as the Federal Reserve's $600 billion program of large-scale asset purchases.

Fiscal policy may also come to the fore in the next few weeks. If elected officials in Washington get serious and start to make tough decisions about what entitlements will be cut and whose taxes will be increased, the outcome could be surprisingly positive for US equity investors, Cliggot said.

S&P index is currently down 14.17 points, or 1.18 percent, to trade at 1,183.67. For the past 52-weeks, the index has been trading in the range of 1,010.91 to 1,227.08.