Precision-casting scarcity → OEM-line allocation priority → aftermarket starved → value transfers from aftermarket-levered suppliers to the constrained-input owner

A precision-casting shortage concentrated in ~2% of suppliers forces scarce turbine/engine components onto Boeing and Airbus OEM lines and away from the higher-margin aftermarket. The allocation rule — not the shortage itself — is the mechanism: it converts a supply constraint into a mix shift that destroys margin at aftermarket-levered names while leaving the constrained-input owner's volume intact. Realized 2026-08-06: Honeywell Aerospace (HONA) cut 2026 guidance $300M and fell ~24%. Tradeable: avoid aftermarket-mix-levered aero suppliers through the constraint; the other side of the transfer is the casting/forging owner (HWM, and possibly the melt tier upstream).

• Step 2: Evidence that the aftermarket is being prioritized over OEM lines, or that allocation is pro-rata rather than OEM-first — which would break the mix-shift mechanism while leaving the shortage intact.
• Step 3: A second aftermarket-levered aerospace supplier reporting aftermarket mix and margin UP through the constraint would indicate HONA's miss was company-specific execution, not the allocation rule.
• Step 4: Casting/forging lead times contracting back toward 12-18 months, or a credible capacity addition landing before 2028, would make this transitory and remove the durable-transfer premise.
• Step 1: Disclosure that the '2% of suppliers' concentration is a Honeywell-specific sourcing decision rather than an industry-structural feature would confine the chain to one company.

• HONA is a newly-separated company missing its first guide as an independent public company — the single most attractive moment to attribute a miss to an exogenous supply shortage rather than to execution or to the guide itself. The GE Aerospace delinquency figure is the independent check and it corroborates, but both names are engine-exposed, so this is one constraint observed twice rather than two independent constraints.
• The beneficiary leg is unevidenced and may not exist. lta-contract-structure-as-price-insulation describes the mechanism by which long-term agreements route exactly this rent to the buyer instead of the constrained supplier. 'Sold out' is a volume fact; 'captures the rent' is a price claim, and nothing here establishes the latter.
• The chain could also be read as demand-destroying rather than value-transferring: if OEMs cannot lift build rates because of the same constraint, casting volume is capped too and nobody captures a rent.

• The direction that is *evidenced* is the negative one: aftermarket-mix-levered aerospace suppliers absorb the shortfall. HONA is the realized instance; the read-across is to any supplier whose margin depends on aftermarket/spares mix rather than OEM shipset volume.
• The positive side of the transfer is the owner of the constrained input — HWM at the casting/forging conversion step (see aerospace-throughput-bottleneck-to-howmet-pricing-power), and possibly one tier further upstream at qualified specialty-alloy melt (see shared-heavy-forging-capacity-to-specialty-alloy-melt-rent). That leg is NOT established here: this mechanism evidences who loses, not who gains.
• Breadth: this sits in industrials / materials ex-AI, a target vertical under the step-2a breadth steer (ai-infrastructure at 48% of chains).
• The same allocation logic appears in a second, unrelated component the same week — the GKN Aerospace window plant halt, where OEM ramp and maintenance-shop replacement demand compete for one constrained part. Two instances of one pattern is what makes it structural rather than idiosyncratic.