What happened

AutoZone (AZO 0.82%) trailed the market last month, falling 13% compared to a 4% decrease in the S&P 500, according to data provided by S&P Global Market Intelligence.

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^SPX data by YCharts.

The decrease kept the auto parts giant's shares significantly below the returns of the broader market, down 10% over the past 12 months.

So what

Investors weren't pleased with AutoZone's quarterly report that was released near the end of the month. That announcement included steady revenue growth as comparable-store sales held steady at 2%. Profitability was positive, too, with gross margin ticking up to 52.9% of sales from 52.7% a year ago.

A shopper picks out windshield wiper fluid.

Image source: Getty Images.

On the other hand, net income just inched higher to miss consensus expectations as the retailer spent more heavily on wages and advertising.

Now what

CEO Bill Rhodes and his executive team recently announced plans to sell their Interamerican Motor Corporation and AutoAnything segments as part of their plans to refocus on their core retailing strengths of catering to both "do-it-yourself" and "do-it-for-me" automotive parts and services shoppers.

Meanwhile, it might take a few quarters, at least, before investors will know whether AutoZone's latest growth slowdown was a temporary speed bump driven by factors like unseasonable winter weather or the start of a disappointing long-term trend as e-commerce giants elbow in on its dominant market position.