May 26 - U.S. auto parts retailer AutoZone AZO.N reported higher third-quarter profit and revenue on Tuesday, driven by resilient demand for maintenance parts and strength in its higher-margin commercial business.

Shares of the company fell 5.3% in premarket trading.

• Strong demand from an aging vehicle fleet, as inflationary pressures and rising new-car prices prompt Americans to hold on to their vehicles longer, has supported sales of replacement parts, boosting earnings of retailers such as AutoZone.

• However, higher costs and inventory investments continue to pressure margins, prompting retailers to lean more on commercial business for growth.

• Peers including O'Reilly Automotive ORLY.O have flagged similar trends, with resilient demand offset by persistent margin pressures.

• AutoZone's gross margin fell to 52.2% from a year earlier, primarily due to a non-cash inventory accounting charge, which was partly offset by underlying margin improvements.

• Overall sales for the quarter ended May 9 rose 8.4% to roughly $4.84 billion from a year ago and were slightly above analysts' average estimate of $4.83 billion, according to data compiled by LSEG.

• Domestic commercial sales rose 10.4% to $1.4 billion in the quarter from a year earlier.

• AutoZone's quarterly net income rose 5.4% to $641.49 million, or $38.95 per share, from last year. Analysts expected a quarterly profit of $36.28 per share.