A Strait-of-Hormuz risk-off unwind spared the defense primes but gutted the drone supply layer — rare-earth, edge-AI and optics names fell 6–9% while Mercury Systems led the decline.

There was no real green in the drone basket on Monday. The nominal leader was Umicore's US line (UMICY), up 0.5% to $5.73 — a fractional bid in a battery- and catalysis-materials name, not conviction. The session was a broad momentum unwind: the S&P 500 fell 0.79% to 7,515.34 and the Nasdaq 1.55% to 25,873.18 after President Trump reinstated what he called a blockade on Iranian shipping through the Strait of Hormuz, with the US and Iran trading attacks and Brent jumping more than 4% to roughly $78.82. The irony is not lost on a chokepoint desk: the tape's own catalyst was a physical strait. The defense primes largely absorbed it — RTX firmed 0.2% to $196.39, L3Harris eased 0.7% to $288.69 — because their backlogs are contracted, not sentiment-priced.

The laggard was Mercury Systems (MRCY), down 9.0% to $98.26. This was profit-taking, not a broken thesis: the stock had rallied hard on a Jefferies note flagging a record ~$1.6 billion backlog and naming it a top mid-cap defense pick, plus optimism around a Blue Raven server order. Monday reassessed how much of that was already in the price. Mercury sits at the processing-subsystem chokepoint — the rugged compute that turns a sensor feed into a fire-control solution — so a de-rate here is a valuation reset, not a demand signal.

The damage concentrated exactly where the supply chain is most speculative and most China-exposed. USA Rare Earth (USAR) fell 6.9% to $17.21 and Unusual Machines (UMAC) 8.5% to $17.22 — the magnet and airframe layer that lives or dies on rare-earth access. Ambarella (AMBA), the edge-AI vision silicon, dropped 6.9% to $72.00 alongside the broader chip selloff, and LightPath (LPTH), the infrared-optics supplier, lost 6.0% to $11.03. The pattern is a leverage sort: the closer a name is to a contested input — neodymium magnets, edge inference, IR glass — the harder it fell, while the integrators held.

The calendar turns dense this week. Wednesday (July 15) brings the House floor vote on the FY27 NDAA (H.R. 8800) and the guided disclosure of Army–RTX Coyote multi-year framework terms; Teledyne reports July 22 in its first print since the LASSO award, and RTX and Iridium both report July 28. Further out, MP Materials' Q2 on August 6 is the domestic-magnet read, and the two hard rare-earth dates still loom — China's suspension of its October 2025 export controls expires November 10, and the gallium/germanium/antimony ban suspension November 27. Monday priced the strait; the magnet supply chain is the chokepoint that actually decides this vertical.