Is One Number Reason Enough To Sell Costco Stock?
About 3 percentage points of Costco Wholesale’s fiscal Q4 2026 sales growth came from higher gas prices. That part of the growth reflects what a gallon cost, not how much members bought. Holders pay a high price for Costco’s growth, so where the growth comes from matters. Why did gas add so much to Costco’s sales in one quarter?
Costco Members Paid More For Each Gallon Of Gas
Management said in the fiscal Q4 2026 call that comparable gas sales rose by a mid-30s percentage. It named a higher price per gallon and record gas volumes as the causes. Only the higher price is counted in the 3 points.
The price rise started outside Costco. Management tied inflation in gas to an ongoing conflict. It said members turned to Costco’s gasoline for value as prices rose. Management also said inflation is difficult to predict, citing the uncertainty around that conflict.
How Much Of Costco’s Growth Is Gas?
Gas accounts for about 3 points of the quarter’s sales growth. Net sales in the fiscal fourth quarter grew 11.2%. Costco’s revenue grew 7.6% a year on average over the past three years.
Higher gas prices also lowered Costco’s margin. Its gross margin is the share of sales left after paying for the goods it sells. That margin was 11.02% in fiscal Q4 2026, down from 11.13% in the same quarter a year earlier. Management said that, excluding gas inflation, the margin rose by 20 basis points. That is a fifth of a percentage point. Costco ended up with more sales and a thinner margin on them.
Is Costco Still Growing Once Gas Is Taken Out?
Yes. Costco’s comparable sales, which leave out newly opened warehouses, rose 6.7% once gas price inflation and currency moves were removed. The reported figure was 9.4%. Gas price inflation added about 3 points to sales and currency moves took off about 0.3 points. Members also shopped more often, with visits up 3.3% worldwide. Management said in the same call that sales excluding gas remain very robust.
Holders pay a high price for that growth. Costco stock trades at 46 times earnings, so a holder pays $46 for each dollar of annual profit. The S&P 500 trades at about 21 times. A price that high likely assumes Costco keeps growing. Costco stock has not risen with reported sales. It lost 0.6% over the past twelve months, while the S&P 500 returned 16.0%.
On these figures, the gas number is a mild worry for a holder of Costco stock. Costco is growing without gas, and its margin rose once gas inflation was excluded. The risk is that gas prices stop rising and reported comparable sales growth falls back toward 6.7%. Costco will announce September sales on Wednesday, October 7, 2026, after the market closes. Comparable sales growth near 6.7%, with gas price inflation and currency moves removed, would show the rest of Costco’s business kept pace. Comparable sales growth well below 6.7% on the same basis would be the first sign that members are slowing their other spending.
Does This Mean You Should Act On COST?
Our purpose is to inform you with unique data so you make the right investment decisions. That said, betting on a single stock is always risky, no matter which direction you choose.
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