Will Costco's trailing P/E ratio compress below 45x at any point before December 31, 2026?

Q2 FY2026 data materially updates the quantitative picture but not the directional thesis. The P/E has naturally compressed from ~54x to ~51-52x through EPS growth alone, which reduces the required stock price decline from ~17% to ~11-14%. This is a genuine improvement in the probability — a smaller price shock is needed. However, the stock trading flat AH signals the market has now fully priced excellent execution; there is no positive re-rating catalyst remaining. The path to 45x still requires an exogenous event: a macro shock, recession fears, or sector rotation. With 10 months remaining and no operational catalyst, I estimate ~20% probability of macro event sufficient to cause 11%+ COST decline plus ~8% for company-specific catalyst (none currently visible), with modest overlap reducing the combined figure. Net: 26%. Slightly lower than the prior 30% opus run 1 because the stock didn't re-rate upward despite strong earnings — the premium is sticky but the hurdle for compression has genuinely shrunk.

The Q2 data simultaneously reduces the required price shock and eliminates any near-term positive earnings catalyst. COST needed to sustain ~14% EPS growth to keep expanding the market's confidence in the premium — it delivered exactly 14% in Q2. The problem: the market is treating this as 'meeting expectations' rather than 'exceeding.' This implies the premium is now priced for continued near-perfection with no margin for disappointment. Over a 10-month window, the probability of at least one meaningful macro shock (tariff escalation, consumer confidence decline, credit event) that could cause a temporary 11-14% drawdown in COST is non-trivial. Historical base rate for COST experiencing an 11%+ intra-year decline is probably 30-35% of years. The 'any point' framing captures temporary touches — COST doesn't need to stay at 45x, just visit. Holding at 30% — the reduction in required price decline is roughly offset by the removal of any remaining earnings catalyst.

Quantitative recalibration: At $980 with FY2026E EPS of $19.30 (14% H2 growth) or $18.80 (8% H2 growth), the trailing P/E is ~50.8x to 52.1x. To reach 45x with $19.30 EPS: stock must fall to $868 (-11.4%). To reach 45x with $18.80 EPS: stock must fall to $846 (-13.7%). The midpoint scenario requires ~12-13% stock decline. COST's defensive profile historically means it participates in broad drawdowns at a ratio of roughly 0.5-0.7x the S&P 500. A 20% broad market correction would be needed to pull COST 12%+ lower. The probability of a 20%+ broad market correction in any given 10-month window is roughly 15-20%. Adding company-specific risks (~8%) and accounting for overlap: ~23-28%. The EPS growth update is mildly favorable (reduces the needed decline) but operationally confirms nothing changes the bear case timing. Settling at 28%.

The Q2 earnings print reinforces that Costco is executing at the highest level, and the market has priced this in with the stock essentially unchanged. This is actually a slight negative signal for compression: the market had already embedded the expectation of strong execution, and strong execution arrived, and nothing changed. This is the hallmark of a stock where multiple compression requires an exogenous shock, not a company-specific trigger. The reduction in required price decline (from ~17% to ~11-14%) is partially offset by the confirmation that operational momentum is intact. I weight the macro shock scenario at ~18% probability over 10 months and the operational deterioration scenario at ~6%. Net: ~24%. Slightly below the prior 0.25 because Q2 confirmed the bull case with no bearish signals emerging.

The 'any point' resolution criterion is critical and often underweighted. By late 2026, if EPS grows to $19.30, the stock only needs to temporarily visit $868 — a level it was trading at roughly 8 months ago in mid-2025. Stock prices revisit recent levels with surprising frequency. The question is not whether the fundamental case for premium will endure (it likely will), but whether the stock will briefly touch a level that it has recently traded at. The 5-year average P/E of 44.67x means that 45x has been fair value for much of the last 5 years — the premium regime only fully asserted itself post-2023. Any re-rating narrative that questions whether the premium regime was temporary could push the stock back toward recent prices. I weight this at 32%: the 'any point' + 'recently traded at similar prices' argument is the most compelling bull case for YES, but it requires a narrative shift that Q2 earnings just made less likely.

The key Q2 update is that COST confirmed the earnings growth engine is intact — but also confirmed the market knew this. A stock that can absorb 14% EPS growth without moving upward has 'perfection priced in' but also demonstrates that the premium has inertia. The compression catalyst would most likely come from: (1) a broad market drawdown in which COST is not a safe haven (possible if inflation fears return and consumer staples are seen as rate-sensitive), (2) a sector rotation away from defensive compounders toward cyclicals or AI infrastructure plays, or (3) a Q3/Q4 miss that changes the narrative. For a 10-month window, I estimate each at ~12%, ~8%, and ~7% respectively, with overlap of ~5%. Net: ~22-26%. Settling at 26% — the EPS growth confirmation modestly reduces the operational miss scenario but the macro paths remain live.

Prior prediction for this model was 22%. Q2 data reduces the required stock decline from ~17% to ~11-14%, which is a genuine improvement. However, the operational confirmation also hardens the bull case — there is now even less reason to expect multiple compression from internal factors. The net effect is roughly neutral: modestly easier price target, but stronger fundamental support for the premium. Nudging to 23%.

The 5-year average P/E of 44.67x remains a useful anchor. The stock is currently ~13% above the level that would correspond to 45x trailing P/E at expected FY2026 EPS. Over a 10-month window, a 13% pullback is within normal historical volatility for individual stocks, even high-quality ones. COST's beta is low (~0.6-0.7) but it is not immune to drawdowns. The 'any point' framing and the proximity to the 5-year average continue to support a probability in the high-20s. Staying near prior estimate of 29-30%.

Base rate reasoning: In any given 12-month window, COST has historically experienced at least one 10%+ intra-year drawdown in perhaps 30-40% of years. Over a 10-month window, this scales to roughly 25-33% probability. With EPS growth reducing the required decline to ~11-14%, a 13% intra-year COST drawdown (consistent with 15-20% broad market correction) would be sufficient. The operational update is net neutral — confirms earnings trajectory but removes any surprise upside catalyst. Rounding to 26%.