Is Costco's Premium Valuation Sustainable Amid Slowing Membership Growth?

Costco Wholesale Corporation (NASDAQ: COST) has long been a darling of the membership retail sector, with its high-margin membership model and disciplined cost structure driving consistent growth. However, as of 2025, the company faces a critical juncture: its premium valuation metrics, including a forward P/E ratio of 43.29 and a PEG ratio of 4.87, appear increasingly stretched relative to its slowing membership growth rates. This raises a pivotal question for investors: Is Costco's valuation sustainable in the face of decelerating membership expansion and intensifying competition from rivals like Sam's Club and BJ's?

Valuation Metrics: A Double-Edged Sword

Costco's financials remain robust, with membership fee income surging 14% year-over-year to $1,724 million in Q4 2025, driven by a 5.2% increase in total paid households to 81.4 million. Executive memberships, now accounting for 74.3% of total sales, have become a cornerstone of recurring revenue. Yet, these strengths are juxtaposed with valuation risks. The company's forward P/E ratio of 42.99 far exceeds the industry average of 30.15, while its P/S ratio of 1.39 and P/BV ratio of 12.79 suggest investors are paying a premium for earnings and sales relative to peers. Analysts project 7.5% sales growth and 11.7% earnings growth for 2026, but these forecasts hinge on "perfect execution" to justify the elevated multiples.

Membership Growth: A Slowing Engine

Costco's membership growth has moderated from 7% in 2024 to 5.2% in 2025, a trend mirrored in its competitors' strategies. Sam's Club, for instance, has accelerated store openings, planning to add 15 new locations annually to counter Costco's expansion. BJ's Wholesale Club, meanwhile, raised membership fees for the first time in seven years in 2025, signaling a shift toward monetizing its growing base. While Costco's U.S. renewal rate remains strong at 92%, the global rate of 90% reflects a slight decline linked to online sign-ups, which may prioritize price over loyalty.

Competitive Resilience: Expansion and Digital Innovation Costco's resilience lies in its aggressive expansion and digital investments. The company opened 27 new warehouses in 2025, pushing its global store count past 900, while digitally enabled sales grew at a double-digit pace. These initiatives aim to offset margin pressures from wage inflation and logistics costs. Additionally, the shift toward higher-tier Executive memberships-now 47.7% of total paid members-has bolstered fee income. However, rivals like Sam's Club are closing the gap with innovations such as "Scan & Go" technology, which could erode Costco's appeal to younger, tech-savvy demographics.

Risks and Macroeconomic Headwinds

Despite these strengths, macroeconomic and competitive risks loom. Tariff pressures on hardline categories could dampen discretionary spending, while thin merchandise margins (12.88% gross margin in Q1 2026) leave little room for error. Moreover, the subscription, membership, and loyalty sector-valued at $3 trillion in 2024-is becoming increasingly crowded, with Amazon Prime and other players vying for market share.

Conclusion: A Tug-of-War Between Growth and Valuation

Costco's premium valuation hinges on its ability to sustain membership growth and outpace competitors. While its digital transformation and expansion strategy provide a long-term runway, the current P/E ratio assumes continued execution without material hiccups. For investors, the key question is whether the company can justify its multiples through innovation and operational efficiency or if the market will demand a re-rating as growth slows. In a sector where membership income is king, Costco's ability to adapt to evolving consumer preferences-and maintain its 92% U.S. renewal rate-will be the ultimate test of its valuation sustainability.