Costco's Strong Q3 Masks Persistent Valuation Risk

What happened

Costco reported fiscal Q3 2026 results on May 28, showing another strong quarter operationally, but the stock's premium valuation remains a hurdle for investors. The company continues to benefit from membership growth, high renewal rates, and robust comparable sales, yet the market has already priced in sustained mid-to-high single-digit comps. At roughly 52x P/E and 32x EV/EBITDA, there is little room for error, and any deceleration in monthly comps or renewal rates could trigger a de-rating. The master report maintains a WAIT rating with an attractive entry near $900, well below the current $996 price, reflecting the lack of margin of safety. Consequently, the strong quarter does not change the thesis that forward returns are limited and downside risk is elevated.

Implication

Costco's Q3 results confirm solid execution, but the stock's valuation already embeds perfection, offering little upside from current levels. The master report's WAIT rating with a $900 attractive entry reflects the need for either a price reset or stronger-than-expected comps and membership trends to justify the multiple. Key risks include any slowdown in monthly comparable sales or renewal rates, which would rapidly compress the premium. Until those variables become clearly favorable or the stock price declines, the risk/reward is unfavorable. Long-term holders may still benefit from the business's durability, but new entrants should wait for a better entry point.

Thesis delta

No material change. Strong Q3 results reaffirm current operations but do not alter the bearish skew from high valuation; the thesis remains that wait for price pullback or clearer upside catalysts is prudent.