For the second consecutive month, Scotiabank’s Commodity Price Index, which measures price trends in 32 of Canada’s major exports, lost significant ground in September, declining 6.8% month-over-month.

While still 24.5% above a year earlier in September, commodity prices will retreat further in October alongside faltering global economic prospects, ushered in by a U.S. and European banking crisis, deleveraging by financial institutions and sharply tighter global credit conditions.

“The decline in commodity prices has been heightened by a massive unwinding of futures and commodity-index investment positions by hedge funds, shifting out of commodity investments deemed too risky in a global deflationary economic environment,” says Patricia Mohr, vp and commodity market specialist at Bank of Nova Scotia. “Investment in commodity index-linked securities fell from about US$200 billion at the end of June to no more than US$150 billion in September and will plunge in October.”

The decline in the Index in September was led by the oil & gas sub-index, with a decline of 10.6% month-over-month and the agricultural sub-index, with a decline of 8.9%, the two sectors where hedge fund outflows from futures markets have been the greatest.

In a bid to shore up market conditions, OPEC announced a cut to its formal production quotas at its October 24 emergency meeting.

“The reduction should largely bring world supplies back in line with demand, though the market remains skeptical that the cut will be enough in view of uncertain global economic conditions,” adds Mohr. “

Medium-term, oil prices are expected to return to the US$85 level.

The metal and mineral index has lost 9.7% since the July 2008 peak and will plunge in October. Both base and precious metal prices dropped in September, with only potash and cobalt bucking the trend.

Base metal prices have moved from boom to bust since mid-July, as investment funds massively exited their positions. While prices are very over-sold, uncertainty over global economic prospects and selling by some funds into rallies are likely to keep prices at a low ebb over the balance of the year.