What Costco Needs to Prove in 2026

Costco Wholesale (NASDAQ: COST) enters 2026 from a position most retailers would envy. Membership growth remains strong, renewal rates are high, and the business continues to compound steadily. Yet the stock also trades at a premium valuation, and expectations are elevated.

For investors, the question is no longer whether Costco is a great business -- that debate is largely settled. Instead, the more relevant question is what the company needs to prove next to justify long-term confidence from here. Three areas stand out.

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Membership growth can stay resilient without constant price hikes

Costco's membership model remains the backbone of its profitability. In 2025, membership revenue reached $5.3 billion, driven by both higher paid memberships and a fee increase implemented in late 2024. Renewal rates held near 90% globally, and even higher in the U.S. and Canada.

In 2026, investors will be watching whether that momentum holds without the tailwind of another fee hike. Costco historically raises prices infrequently, and that restraint is part of why trust in the brand runs so deep. However, it also means that future membership growth needs to come more from volume than from pricing.

That puts the focus on two things: net new paid memberships and renewal quality in newer markets. If paid memberships continue to grow at a healthy clip and renewal rates remain stable after the increase, it would reinforce the idea that Costco's membership value proposition is still strengthening organically. A noticeable slowdown, on the other hand, wouldn't break the story, but it would temper expectations for profit growth.

International expansion can scale profitably, not just quickly

Costco's long-term growth story increasingly depends on markets outside the U.S. The company now operates more than 900 warehouses globally, yet still has limited penetration in large, high-income regions. China, in particular, has drawn outsize attention after early stores saw strong traffic and demand.

In 2026, the key isn't whether Costco can open more international warehouses -- it can. The question is whether those stores can mature into high-quality, high-renewal membership bases comparable to those in North America. That takes time, local execution, and discipline.

International expansion also presents structural challenges, including real estate costs, supply chain complexity, and cultural differences in shopping behavior. Costco's low-price model travels well, but not without friction. Investors should watch store economics, renewal trends, and operating margins in newer regions rather than focusing solely on headline store counts.

If Costco can show that international warehouses deliver strong returns without eroding margins or brand trust, it would meaningfully extend the company's growth runway well into the next decade.

Earnings growth can grow into a premium valuation

Costco's valuation remains one of the most debated aspects of the stock. Shares trade at a multiple well above both retail peers and the company's long -term historical average. That premium reflects confidence in Costco's durability, but it also leaves little margin for disappointment.

In 2026, investors will be seeking continued earnings growth driven by a combination of operating leverage, steady sales growth, and expanding membership income. Costco doesn't need dramatic margin expansion, but it does need to demonstrate that scale and efficiency continue to translate into a positive bottom-line impact over time.

Importantly, this isn't about short-term stock performance. Costco has looked "expensive" for much of the past decade and still rewarded patient shareholders. The real test is whether earnings growth stays strong enough to justify today's valuation over a multiyear horizon.

If earnings compound steadily and membership economics remain intact, valuation concerns may fade into the background. If growth slows meaningfully, however, the premium could come under pressure even if the business remains fundamentally healthy.

What does it mean for investors?

Costco doesn't face any existential test in 2026. Instead, it faces a credibility test -- one that applies only to companies operating from a position of strength. Investors already believe in the model. Now they want confirmation that it can scale globally, sustain organic membership growth, and compound earnings into a premium valuation.

If Costco executes across those three fronts, it won't just justify its place as a retail leader -- it will reinforce why long-term investors continue to treat it as one of the market's most reliable compounders.

For investors, 2026 will be a year to observe if Costco can continue its world-class execution.

Lawrence Nga has no position in any of the stocks mentioned. The Motley Fool has positions in and recommends Costco Wholesale. The Motley Fool has a disclosure policy.