Costco Q4 Sales Grew 13% As Gas Prices Lifted Revenue

Costco Wholesale reported that gas price inflation lifted its fiscal Q4 2026 sales by approximately 3%. Management disclosed this figure during the earnings call held on September 24, 2026. The retailer's comparable sales rose 9.4% for the quarter, a figure that dropped to 6.7% after excluding the effects of gas prices and currency fluctuations. Gasoline sales themselves expanded significantly, with management citing a mid-30s percent increase in comparable gas sales driven by higher per-gallon prices and record volumes.

The current valuation of Costco shares reflects investor expectations for sustained growth. The stock trades at 45.6 times earnings, a multiple that exceeds the S&P 500 valuation. This premium sits in the upper half of the company's ten-year historical range. Such a high multiple leaves limited room for error if sales growth slows. In 2022, Costco stock experienced a peak-to-trough decline of 31%, outpacing the S&P 500's 25% drop over the same period.

While higher gas prices boosted revenue, they compressed the company's profitability margins. The reported gross margin rate for fiscal Q4 2026 fell by 11 basis points year over year to reach 11.02%. However, management stated that excluding gas inflation, the margin rate would have been 20 basis points higher than the prior year. This dynamic suggests that a decrease in fuel costs could pressure total sales figures while simultaneously improving the gross margin rate.

Management attributed the elevated costs of gas and motor oil to the ongoing conflict in the Middle East. They noted that the situation remains uncertain and that predicting inflation trends is difficult. Barron's reported on October 8, 2026, citing a Wall Street analyst, that part of the September sales jump included one-off, lower-margin items. Despite these external factors, core business metrics show strength. Worldwide shopping frequency increased by 3.3% in fiscal Q4 2026, and management described sales excluding gas as very robust.

Membership retention also improved slightly. The renewal rate in the U.S. and Canada reached 92.3%, marking a 10 basis point increase from the previous quarter. The company's financial position remains strong, with an operating profit over the last twelve months that was 80.6 times its interest expense.

Monthly data provides further context on the underlying growth rate. Costco published its September sales results on October 7, 2026. Comparable sales for that month rose 11.4%, a figure that adjusted to 7.6% when excluding gasoline and currency effects. If this underlying growth rate persists while gas prices decline, it would indicate that the company's expansion does not rely on high fuel costs.