In a previous article I pointed out how copper contango/backwardation correlates with the copper price. Since June 11th 2012, copper went back into contango which isn't boding well for copper prices (Chart 1). The China PMI is also going down lately, which means demand for commodities from China will be sluggish.
As copper correlates with the S&P, I would imagine that stock markets will go down too in the future. So investors should act accordingly and sell equities at this moment.
|Chart 1: Copper Contango Curve|