Costco's Q4 US Comp Surges 10.7%, But Quality Metrics Remain Unclear

What happened

Costco's fiscal Q4 2026 U.S. comparable sales rose 10.7%, according to Zacks, driven by higher traffic, larger baskets, and resilient member spending, signaling continued domestic momentum. This headline figure surpasses the company's recent quarterly comps, but it likely includes gasoline inflation, which has historically inflated reported sales by several hundred basis points. The DeepValue master report rated Costco a WAIT at $949.50, arguing that the stock's 47.7x P/E and 30.7x EV/EBITDA already discount strong operating performance. The new report only provides the top-line U.S. comp number, omitting critical adjusted comp (ex-gas) and digitally-enabled comp data needed to assess growth quality. Unless adjusted comp remained near 6-7% and digital comp stayed above 20%, the 10.7% print may be as much fuel optics as fundamental acceleration, leaving the valuation concern intact.

Implication

For investors, the 10.7% U.S. comp is encouraging but insufficient to change the valuation calculus. The key question is whether this growth is broad-based or inflated by gasoline prices, which would not support the premium multiple if underlying demand is weaker. If Q4 adjusted comp stayed around 6-7% and digitally-enabled comp held near 20%, the base case remains intact and the stock may drift toward the $1,025 trim level. However, if adjusted comp fell below 5% or renewal slipped, the bear case gains probability and downside to $820 is plausible. Given the article's lack of detail, investors should hold positions and await the full Q4 earnings release before acting.

Thesis delta

The new U.S. comp print of 10.7% is above prior quarters but likely includes gasoline inflation, so it does not by itself shift the thesis. The WAIT rating rests on adjusted comp, digital growth, and renewal quality, none of which are provided in the article. Until those details are available, the thesis remains unchanged: valuation offers no margin of safety, and the next reports must confirm durable growth to justify the price.