North American markets may open lower Monday on Monday, as concerns about the health of the U.S. economy were reignited over the weekend by Wal-Mart Stores’s below-forecast October sales.

Wal-Mart over the weekend said same-store sales rose just 0.5% in October, its smallest rise in nearly six years. It had previously forecast a sales rise between 2% and 4%.

Here at home, prices for manufactured goods at the factory gate declined in September for the second month in a row, mainly due to lower prices for petroleum products, Statistics Canada reported today.

Raw materials prices also decreased in September, as prices for crude oil continued to fall.

Prices charged by manufacturers, as measured by the Industrial Product Price Index (IPPI), were down 1.6% in September, following a 0.5% drop in August, StatsCan said. Lower prices for petroleum products were the major contributors to this monthly decrease.

The 12-month change in the IPPI was up 1.3%, a lower rate of growth compared to the year-over-year increase of 3.6% in August. Upward pressure came mainly from higher prices for primary metal products.

The Canadian dollar opened at US89.12¢, down 0.25 of a cent.

South of the border, U.S. personal income growth picked up steam in September, while personal spending slowed and a key inflation indicator eased slightly.

Personal income grew in September at a seasonally adjusted rate of 0.5%, after increasing a revised 0.4% in August, the U.S. Commerce Department said today.

August income growth was previously reported at 0.3%. Meanwhile, personal consumption grew 0.1% in September, less than the revised 0.2% increase the month before. August spending growth had previously been reported at 0.1%.

Overseas, unchecked global warming will devastate the world economy on the scale of the world wars and the Great Depression, a major British report said Monday.

Gold futures climbed, with the December contract up $6.10 an ounce to US$607.10. Crude-oil futures declined 69 cents to US$60.08 a barrel.

Concerns over the U.S. economy lingered over international stock markets on Monday. The Nikkei 225 tumbled 317 points, or 1.9%, in Tokyo. The German DAX 30 declined 0.7%.

Hong Kong’s financial markets were closed for a holiday.

Toronto stocks fell Friday, as a poor day in information technology sector and in the broader market overall, led investors to sell off recent gains.

The S&P/TSX composite index fell 66.82 points, or 0.54%, to 12,268.86.

The benchmark index finished the week 233.29 points higher.

The S&P/TSX Venture composite index gained 11.18, or 0.44%, to 2,540.43.

In New York, markets ended the week lower, breaking a run of positive gains, on negative economic reports and disappointing corporate earnings news.

The Dow Jones industrial average lost 73.40 points, or 0.60%, to 12,090.26, the S&P 500 dropped 11.74, or 0.85%, to 1,377.34, and the tech-heavy Nasdaq composite index gave up 28.48 points, or 1.20%, to 2,350.62.

For the week, the Dow gained 0.8%, the S&P 500 lifted 0.7% and the Nasdaq advanced 0.4%.