(Bloomberg) -- Costco Wholesale Corp. slipped in late trading as the second straight slowdown in a key monthly sales gauge stoked doubts about the strength of US consumers.

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US comparable sales eked out only a 0.9% gain in March after excluding the impact of changes in gasoline prices, the company said in a statement Wednesday. That’s the smallest advance since April 2020 — shortly after the economic lockdowns at the start of the pandemic.

The tepid performance underscored the risk that Costco’s long sales boom is finally petering out. It also adds another sign of weakness in the US economy the same day that the Institute for Supply Management reported slower-than-expected growth in the US service sector in March.

Costco dipped 2.4% in after-hours trading in New York. The shares advanced 8.9% this year through the close on Wednesday, topping the 6.5% gain in the S&P 500 index.

The retailer reported US comparable sales of more than 6% in December and January, but that decelerated to 3.5% in February. While Costco’s upscale customers have been less affected by inflation, the warehouse club isn’t immune to softer sales of discretionary items as shoppers spend more on basic goods and services such as travel.

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