North American stocks may open lower Tuesday as key U.S. retailers came out with mixed quarterly results.

Retail behemoth Wal-Mart reported a 19% increase in net income, but the company cut its earnings outlook for the year, saying underlying performance during the second quarter was not what it expected and that many of its customers are under economic pressure.

Home Depot reported a 15% decline in net income and said it sees housing market weakness extending into 2008.

In today’s economic news, Canada’s merchandise exports declined for the third straight month in June in the wake of the largest drop in the machinery and equipment sector in 15 months.

At the same time, imports rose marginally. As a result, Statistics Canada said the nation’s merchandise trade surplus with the world narrowed to $5.3 billion in June from $5.9 billion in May.

South of the border, U.S. July wholesale prices jumped for a fifth time in six months on sharply higher energy prices, though excluding volatile food and energy, underlying cost pressures were under control.

Meanwhile, the U.S. trade deficit narrowed in June as exports of industrial supplies surged, even though crude oil imports rose to their highest level since September 2006.

In other earnings news, UBS reported a 79% increase in second-quarter profit, but warned second-half earnings would be lower than last year amid the market turmoil.

Crude-oil futures rose 29¢ to US$71.61 a barrel.

Overseas, the Nikkei 225 rose 0.3% in Tokyo. The FTSE 100 rose 0.1% in London.

Toronto stocks closed lower Monday, after spending most of the session in positive territory, as losses in the financial sector, still beset by investor worries over the tightening credit environment, pulled down the broader market.

The S&P/TSX composite index fell 38.83, or 0.29%, to 13,427.45, after hitting a high of 13,652.64 earlier in the trading day.

Six of the 10 TSX main sub-groups finished higher.

Financials lost 1.32%.

In New York, markets ended moderately lower after investor optimism earlier in the day gave way to pessimism over the consequences of the U.S. subprime mortgage fallout.

The Dow Jones industrial average drifted down 3.01 points, or 0.02%, to 13,236.53, the Nasdaq composite index ticked lower 2.65, or 0.10%, to 2,542.24, while the S&P 500 edged down 0.72, or 0.05%, to 1,452.92.