NEW YORK - Auto parts retailer AutoZone Inc. said Wednesday its fiscal fourth-quarter profit fell 3.1 percent, citing tough comparisons to a prior-year period that included an extra week of sales. Its shares fell more than 6 percent in midday trading.

Bill Rhodes, AutoZone's chairman, president and chief executive, said consumers remained focused on trying to save money during the quarter by keeping their cars on the road longer and spending more on basic maintenance.

Rhodes added that he expects the same trend to continue for the near future.

"This quarter we continued our focus on the basics," he told investors in a conference call. "And we continue to believe well positioned to take advantage of opportunities as we head into a new fiscal year."

For the quarter ended Aug. 29, the Memphis, Tenn.-based company earned $236.1 million, or $4.43 per share, down from $243.7 million, or $3.88 per share, a year ago. The per-share figures rose because it had fewer shares outstanding in the latest period.

The profit fell short of average Wall Street predictions. Analysts polled by Thomson Reuters expected a profit of $4.45 per share for the latest quarter.

Sales rose 1 percent to $2.23 billion from $2.21 billion and matched analysts' estimates.

Excluding sales from the additional week included in the prior year's quarter, AutoZone said sales rose 7.1 percent and domestic same-store sales - or sales at stores open at least a year - increased 5.4 percent.

AutoZone shares fell $9.92, or 6.5 percent, to $143 in midday trading.

The company said it got a boost from improved efficiencies in how it ships its products and lower fuel costs, but said those benefits were offset by a shift in its sales mix to lower margin products.

Rhodes said that as in recent past quarters, a greater portion of the company's sales were purchases of maintenance items such as oil and filters, break pads and shocks and struts. Discretionary purchases made up less than 20 percent of the quarter's sales, he said.

The CEO added that the government's Cash for Clunkers program - which offered cash incentives to consumers who swapped older, less fuel efficient vehicles for new ones - didn't have a material impact on AutoZone's fourth-quarter sales, noting that the average age of vehicles on American roads continues to rise.

For the full fiscal year, AutoZone earned $657 million, or $11.73 per share, up from $641.6 million, or $10.04 per share, in the pervious year. Sales rose to $6.82 billion from $6.52 billion.

During the quarter AutoZone opened 58 new stores, closed one store, and replaced three stores in the United States. It also opened 20 stores in Mexico. As of Aug. 29, AutoZone had 4,229 stores in the U.S. and 188 stores in Mexico.

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