TORTONTO (Bloomberg) — Canadian stocks extended a slump, led lower by Suncor Energy Inc. and other energy producers, on concern that demand will weaken for oil, as prices dropped to 19 month-low and fuel stockpiles grew in the US.Raw-materials companies, paced by aluminum maker Alcan Inc., helped limit losses in the market, as copper prices gained the most in three months and Alcoa Inc. reported earnings that exceeded analysts’ estimates.

The Standard & Poor’s/TSX Composite Index slipped 10.44, or 0.1 percent, to 12,457.55 in Toronto. The benchmark dropped for a fifth time in seven days and is down 3.5 percent this year.

“Commodity prices and stocks are vulnerable to slower growth,” said Scotia Capital strategist Vincent Delisle in Toronto. Alcoa’s results are “not enough to alleviate fears about commodities”.

Earnings expectations are “too optimistic,” because “analysts have not yet adjusted their forecasts for lower prices,” he said.

Crude oil for February delivery closed 2.9 percent lower at $54.02 a barrel in New York, the lowest since June 10, 2005, after mild weather in the northeastern US, the biggest energy consumer, curbed demand for distillate fuels. A US Energy Department report showed that heating oil and gasoline stockpiles increased last week for the fourth straight week and the most since January 2004.

An index of energy stocks lost 1.1 percent, while a raw-materials gauge rose one percent. The two measures, which account for more than two-fifths of the S&P/TSX’s value, have lost 7.8 percent and 5.4 percent, respectively this year, leading the Canadian stock benchmark down as commodity prices plunged.