In 2008 and 2011, when Copper broke below rising support, the 500 index soon followed. 

At this time Copper finds itself nearing the end of a flag/pennant pattern at (2) in the above chart.  Odds are pretty high that a breakdown in Copper would “Drag” the 500 index to lower prices! 

Copper futures have been pretty boring of late, which is typical towards the end of a flag pattern.  Including todays decline, the S&P is down around 5% from its March highs, not too large of a decline.  Keep a very close eye on what Copper does in the upcoming weeks, due to this key flag pattern.