This guy argues that the correlations between DJ-AIG commodities index and S&P have been increasing. He only has two years’ worth of data, and you can draw a trend line through any two points of data, but his argument makes sense to me:

Not so coincidentally, commodity index ETFs made their debut in 2006. These portfolios, and the ETNs that followed, opened up new, relatively low-cost portals to commodity exposure for investors. A lot of new money has poured into the commodities asset class relying on a history of low correlation. Only time will tell if that reliance will be rewarded.

Brad Zigler, “Early Morning Musing: Correlations Rising?”

What do you guys think?