Research cutoff: September 25, 2026. Costco had reported fiscal fourth-quarter and full-year 2026 results on September 24, with September sales scheduled for October 7. This guide uses confirmed company disclosures and conditional scenarios; it does not invent a price target or future result.
Costco enters October with double-digit quarterly sales growth, strong digitally enabled demand and rising membership-fee revenue, but investors should separate recurring operating momentum from gasoline, currency and a one-time tariff-refund benefit. The October case turns on comparable sales, traffic, membership economics, merchandise margin and expense discipline.
The confirmed fiscal Q4 baseline
Costco’s official fiscal Q4 release reported quarterly net sales of $93.873 billion, up 11.2% year over year. Full-year net sales increased 10.1% to $297.247 billion. Quarterly net income was $2.998 billion, or $6.75 per diluted share, compared with $2.610 billion, or $5.87 per share, a year earlier.
The quarter contained 16 weeks, so comparisons should use the company’s stated year-over-year periods rather than mixing the result with a standard 12- or 13-week retailer quarter. Full-year figures provide a useful second lens when quarterly timing or holiday shifts affect demand.
Comparable sales and traffic quality
Total-company comparable sales increased 9.4% in the quarter. Excluding gasoline-price and foreign-exchange effects, adjusted comparable sales rose 6.7%, including 7.2% in the United States, 4.6% in Canada and 6.2% across other international markets.
The adjusted figures are the cleaner measure of underlying retail demand, but they still combine traffic, ticket size and mix. October research should ask whether shopping frequency remains healthy, whether discretionary categories participate and whether food inflation or product mix drives the average ticket. A headline sales rate alone cannot answer those questions.
Digitally enabled momentum
Digitally enabled comparable sales grew 19.5% as reported and 19.8% after gasoline and currency adjustments. That pace materially exceeded company-wide adjusted comparable growth.
Digital growth can deepen member engagement and broaden convenience, but fulfillment cost and category mix matter. Investors should compare delivery, warehouse pickup and marketplace activity with gross margin and selling expense rather than assuming every online dollar carries the same economics as warehouse traffic.
Membership-fee durability
Membership fees were $1.850 billion in fiscal Q4, up from $1.724 billion a year earlier. For the full year, fees reached $5.907 billion versus $5.323 billion. Membership income is strategically important because Costco prices merchandise at narrow margins and uses the membership model to reinforce loyalty and renewal.
Track paid household growth, Executive-member penetration, renewal rates and fee timing together. Higher fees can lift revenue, but the durable test is whether members continue to see value through prices, assortment and service. Fee growth should not be read separately from retention and comparable sales.
Profit quality and the tariff-refund adjustment
Costco said fourth-quarter EPS benefited by $0.15 from a non-recurring IEEPA tariff refund, net of partial reinvestment in additional member value. That item should be removed when estimating a repeatable quarterly run rate.
Operating income was $3.801 billion versus $3.341 billion a year earlier. Investors should test merchandise margin, shrink, freight, labor and pre-opening expense against sales growth. Reinvestment in member value can pressure near-term margin while strengthening loyalty; the appropriate assessment depends on subsequent traffic and renewal evidence.
Cash generation and expansion
Full-year operating cash flow increased to $15.825 billion from $13.335 billion. Costco ended the fiscal year with 939 warehouses, including 647 in the United States and Puerto Rico, and maintained e-commerce operations across multiple international markets.
Warehouse openings can expand the addressable member base but require land, construction, inventory and staffing. Compare capital expenditure with operating cash flow, new-unit productivity and mature-club sales. Strong cash generation supports growth and shareholder returns, yet expansion quality matters more than the number of openings alone.
The confirmed October event
Costco’s investor calendar lists September sales results for October 7, 2026. That update can provide an early read on post-quarter demand. It should be interpreted with calendar effects, gasoline prices, currency and regional mix rather than treated as a complete earnings report.
Three conditional October scenarios
Constructive: adjusted comparable sales remain broad, digital growth stays efficient, membership economics strengthen and reinvestment supports traffic without material margin erosion.
Mixed: sales and fees grow, but the pace moderates after a strong quarter while wage, shrink or fulfillment costs absorb operating leverage.
Risk: discretionary demand weakens, traffic slows or member-value investments fail to produce retention and volume. Reassess from October 7 evidence rather than assigning an unsupported target.
October investor checklist
- Use adjusted comparable sales alongside reported growth.
- Separate traffic, ticket and inflation effects.
- Compare digital growth with fulfillment economics.
- Track membership fees with renewals and paid households.
- Remove the $0.15 one-time EPS benefit from recurring analysis.
- Measure expansion against cash flow and unit productivity.
- Update the scenario after the October 7 sales release.
Use our September Costco analysis as the prior monthly baseline. Our earnings-report checklist helps separate recurring performance from one-time items.
Frequently asked questions
What were Costco’s fiscal Q4 2026 net sales?
Costco reported $93.873 billion of net sales, up 11.2% year over year.
When are Costco’s September 2026 sales due?
The company lists the sales update for October 7, 2026.
What is the main October risk?
The main risk is that adjusted comparable growth or traffic slows while labor, shrink, fulfillment and member-value investments limit operating leverage.
Educational analysis only; not individualized investment, legal or tax advice. Company materials were checked September 25, 2026 and can be superseded.