MEMPHIS, Tenn. -- Auto parts retailer AutoZone said Wednesday its fiscal fourth-quarter profit fell 3.1 percent, missing Wall Street expectations on tough comparisons to a prior-year period that included an extra week of sales, according to The Associated Press.

The company said its gross margin got a boost from improved distribution efficiencies and lower fuel costs, but said that was offset by a shift in its merchandise sales mix to lower margin products.