Will Costco report healthcare costs exceeding sales growth for 3+ consecutive quarters by Q4 FY2026?

The Q2 earnings call is near-dispositive against YES resolution. The resolution criteria requires healthcare cost growth exceeding sales growth in BOTH Q2 AND Q3 FY2026. Two independent signals in Q2 strongly imply the streak broke: (1) Operations SG&A improved 2bps ex gas deflation — if healthcare were still outpacing sales growth, operations SG&A would have deteriorated, not improved; (2) Management explicitly called out healthcare as a headwind in Q1 but was silent in Q2 — this is a deliberate signal from management known to be transparent about cost drivers. The only remaining YES scenario is if the 10-Q reveals healthcare costs technically exceeded sales growth despite operations SG&A improvement (perhaps offset by other productivity gains within ops). This scenario is possible but requires healthcare to have been a cost headwind that was masked by other improvements — unlikely given management's granular discussion of cost drivers. Residual 18% probability reflects 10-Q ambiguity and the possibility that measurement conventions differ from inference.

Bayesian update analysis: Prior YES probability was 0.55 based on management's Q1 'structural' characterization and healthcare macro trends. Q2 evidence is strongly negative: operations SG&A improvement of 2bps is a real observed outcome, not an absence of data — it is actively inconsistent with healthcare costs exceeding sales growth unless other ops improvements exactly offset and management chose not to mention it. P(ops SG&A improves | healthcare exceeding sales growth) is perhaps 5-10% — it would require other operational efficiencies of sufficient magnitude to mask the healthcare drag while management simultaneously elected not to disclose the continuing headwind. P(management silence | healthcare still a headwind) is also very low — Costco's management is known for cost transparency and explicitly highlighted Q1's healthcare headwind; continuing the issue while not mentioning it would be unusual. Combining these: the posterior YES probability should be in the 10-20% range. 15% reflects residual 10-Q ambiguity only.

The Q1 'structural' characterization drove the prior 55% probability — that prior is now effectively falsified for Q2. The structural thesis assumed healthcare cost inflation (BLS 7-10% annually) would persistently outpace Costco's sales growth. But Costco's Q2 operations SG&A improvement suggests the productivity offset materialized faster than expected. The 20% residual YES reflects two considerations: (1) there is a non-trivial chance (perhaps 20-25%) that the 10-Q shows healthcare costs technically exceeded sales growth even as operations SG&A improved through other line-item improvements; (2) even if Q2 is confirmed NO, the resolution criteria's wording requires 'consecutive' quarters starting from Q1 — so Q2 data point breaks the streak regardless of Q3 outcome. I weight slightly higher than Run 2 because the operations SG&A improvement is reported ex gas deflation, introducing a small measurement complication — the raw reported figure was 2bps better, but the ex-gas figure could be distorted by gas mix effects that happen to mask healthcare. This is a thin concern but warrants slightly higher residual probability.

The Q2 data materially resolves the key uncertainty from the prior prediction. The prior 55% YES was predicated on management's 'structural' characterization continuing into future quarters — the central question was whether macro healthcare inflation would persist faster than sales growth. Q2 answers this with two converging signals: operations SG&A improved 2bps AND management said nothing about healthcare. The resolution mechanics are also favorable for NO: the consecutive streak starting Q1 needs Q2 AND Q3 both positive. If Q2 broke the streak — which the data strongly suggests — the market is already resolved NO regardless of Q3. The 17% residual probability primarily reflects: (1) possibility that the 10-Q discloses healthcare in a technical sense exceeded sales growth despite the ops improvement (perhaps other ops efficiency gains masked it), and (2) any ambiguity in how 'management commentary' is used as an inference bridge vs. hard 10-Q data.

Assigning slightly higher residual probability than other sonnet runs because the inference chain from earnings call commentary to healthcare cost growth has multiple steps with uncertainty at each link. The chain is: (1) management chose not to mention healthcare → (2) this implies healthcare was not a notable headwind → (3) which implies healthcare cost growth did not exceed sales growth. Steps 1-2 are reasonably strong given Costco management's transparency, but step 2-3 has some slack — management might not mention healthcare even if it technically exceeded sales growth if the magnitude was smaller than Q1 (perhaps they have a threshold for disclosure). Additionally, the operations SG&A improvement of 2bps is directionally correct but small — if healthcare were, say, 1bp headwind and other ops productivity was 3bps positive, operations SG&A could improve by 2bps while healthcare still technically exceeded sales growth. The resolution criteria language 'falls below sales growth' needs precise interpretation. These layers of inference uncertainty warrant 22% rather than 15-18%.

The prior prediction's conditional probability decomposition was P(Q2 exceeds) ≈ 0.75-0.80 × P(Q3|Q2) ≈ 0.80-0.85 = ~0.62 YES. Q2 earnings have now effectively resolved P(Q2 exceeds) to approximately 0.15-0.20. This alone collapses the YES probability dramatically: 0.18 × 0.80 = 0.14, even holding P(Q3|Q2) constant. But P(Q3|Q2) is also irrelevant because consecutive streak structure means Q2 break resolves NO — no need to even evaluate Q3. The 16% residual is essentially the probability that our inference is wrong about Q2 (i.e., the 10-Q shows healthcare did exceed sales growth despite the ops improvement and management silence). This is a low but non-zero probability. The collapse from 55% to 16% reflects the data quality improvement — we've gone from 'management says structural, macro trends suggest continuation' to 'Q2 ops improvement actively contradicts continuation.'

Q2 data breaks the prior bull case. Management was silent on healthcare (after explicitly flagging Q1). Ops SG&A improved 2bps. These are converging negative signals for YES resolution. Resolution criteria requires Q2 AND Q3 consecutive — Q2 evidence strongly suggests NO on Q2, which resolves the whole market NO. Residual 18% = probability 10-Q shows something different than earnings call implied.

Simple signal count: two strong NO signals (ops SG&A improved, management silent on healthcare) vs. zero YES signals in Q2 data. The macro healthcare inflation thesis that drove the prior 55% is now contradicted by actual operating results. Management doesn't stay silent on structural cost headwinds — they called Q1 out specifically. 15% captures tail risk from 10-Q ambiguity. Market is very likely to resolve NO.

Slightly elevated vs. other haiku runs because the prior thesis had a legitimate macro foundation — BLS healthcare inflation at 7-10% annually doesn't reverse in one quarter. The Q2 data suggests productivity improvements offset the healthcare drag rather than healthcare inflation itself reversing. This means the underlying macro pressure may still be there, just masked by other efficiency gains. The 20% residual reflects: if the 10-Q shows healthcare still technically exceeded sales growth but was offset by warehouse productivity gains within the ops SG&A bucket, YES could still be alive. The resolution market will ultimately be scored on management commentary and/or 10-Q disclosure, not on inferred net SG&A movement. That resolution methodology ambiguity keeps probability slightly elevated.