Costco (COST) Stock Sinks As Market Gains: Here's Why

Costco (COST) recently underperformed the broader market and its sector, declining 2.34% on the latest trading day and 1.21% over the past month. Despite analyst consensus projecting robust year-over-year growth for its upcoming September 25, 2025 earnings report (EPS +12.43% to $5.79, revenue +8.08% to $86.14B), the stock trades at a significant valuation premium with a Forward P/E of 49.33 and PEG ratio of 5.51, both well above industry averages. This performance divergence and premium valuation make the impending earnings release critical, particularly given a recent 0.35% decline in consensus EPS estimates and the stock's current Zacks #3 (Hold) rank.

Analysis

Costco (COST) is exhibiting a notable divergence between its recent stock performance and forward-looking analyst expectations. The stock has underperformed, with a 2.34% decline in the latest session against a rising S&P 500 and a 1.21% drop over the past month, lagging both its sector and the broader market. Despite this bearish price action, consensus estimates for its upcoming September 25, 2025 earnings report remain robust, projecting a 12.43% year-over-year increase in EPS to $5.79 and an 8.08% rise in revenue to $86.14 billion. However, this optimism is tempered by a premium valuation; the stock trades at a Forward P/E of 49.33 and a PEG ratio of 5.51, both more than double their respective industry averages of 22.01 and 2.64. Further indicating a cautious outlook, the Zacks Consensus EPS estimate has seen a minor 0.35% downward revision over the last month, and the stock currently holds a Zacks Rank of #3 (Hold). The full-year forecast also presents a potential anomaly, with EPS growth of 11.55% paired with a projected 0% change in revenue, suggesting expectations for significant margin expansion.

Key Decisions for Investors

• Investors should weigh the strong consensus earnings growth forecasts against the stock's significant valuation premium, as its Forward P/E of 49.33 suggests high expectations are already priced in, leaving little room for disappointment.
• The upcoming September 25th earnings report is a critical catalyst; failure to meet or exceed the projected 12.43% EPS growth could trigger a valuation-based correction.
• Monitor for any further downward revisions to analyst EPS estimates, as the recent 0.35% decline could be an early signal of moderating business trends ahead of the earnings release.
• Given the stock's recent underperformance relative to its sector, positions should be managed with an awareness that the market may be questioning the sustainability of its premium valuation.