Moody's on May 16 affirmed all ratings of O'Reilly Automotive Inc., including its Baa1 senior unsecured rating, citing the U.S. automotive parts supplier's "exceptional operating performance."

The ratings outlook is stable to reflect Moody's expectation that O'Reilly will continue to execute its operating strategy. The auto parts retailer operates over 5,300 stores in 47 U.S. states.

O'Reilly's senior unsecured shelf and senior unsecured regular bond also were affirmed.

The agency said O'Reilly's exceptional operating performance has led to a strong quantitative profile. It added that O'Reilly has a favorable market position in the auto parts retail segment, a fairly well-diversified geographic footprint and a well-balanced, do-it-yourself and do-it-for me revenue mix. Moody's also highlighted the company's sophisticated distribution infrastructure and product expertise.

The rating agency said it could upgrade the ratings if O'Reilly's financial policy continued its historically predictable course, particularly surrounding shareholder returns and acquisition strategy.

A downgrade is likely if O'Reilly shows a weakened operating performance or a more aggressive financial policy that could result in key credit metrics deteriorating.