Hyundai jumped 8% in Seoul on a humanoid-business review while Japan's motion-control choke sold off on rotation into Korean humanoid and US vision names.

The platform-and-integrator choke led, from Seoul. Hyundai Motor rose +8.2% in its own session to ₩453,000 on a stack of catalysts: reports that the group is reviewing an expanded humanoid-robot business across its tier-one suppliers, core-auto earnings-recovery hopes as the first-half supplier-fire disruption resolved with Q2 seen as the trough, and a GV80 hybrid launch alongside record July exports. Hyundai owns Boston Dynamics, which is what puts it at the robot-platform choke rather than merely in the auto complex — and Friday's move was as much about the market pricing an in-house humanoid roadmap as about the car cycle. Because this is a Korea-listed name, the move reflects its Seoul session, not the US tape.

The laggard was the speculative micro-cap end of the same layer. Knightscope fell −6.2% to $1.52 on no company news — a high-volatility security-robot name giving back ground in a session with a strong humanoid bid elsewhere. At the platform choke, unprofitable micro-caps swing hardest on sentiment, and Friday's rotation simply did not include them.

The day's real chokepoint story was in Japan. The motion-control layer — the strain-wave gears, RV reducers, ball screws and precision bearings that every humanoid joint depends on — sold off even as the Nikkei rose, a clean sector rotation rather than a currency or broad-tape move. Harmonic Drive fell −4.9% to $41.00 at the strain-wave-gear choke, with Nabtesco −3.6% (RV reducers), THK −3.6% (ball screws and linear guides) and Fanuc −3.5%. Money moved out of the Japanese factory-automation incumbents and into the Korean humanoid and US machine-vision plays: Cognex rose +6.6% to $65.63 at the vision-sensing choke, with Symbotic +2.2% and Teradyne +2.0%. The rare-earth magnet choke firmed on policy positioning — USA Rare Earth +7.5% to $20.00, MP Materials +5.5% to $58.74 — though on no dated catalyst.

The calendar builds toward late August. NVIDIA reports August 26 — the demand signal under the robot-brains choke — with Ambarella the same day at the edge-vision layer, and THK reports fiscal Q2 on August 31, the next read on the Japanese motion-control names that led the tape down. Tesla's Optimus V3 reveal is targeted for this summer, the ABB Robotics divestiture to SoftBank is expected to close in the second half, and NVIDIA's Isaac GR00T reference humanoid is due to ship from Unitree late in the year. The tell to watch is whether the rotation out of Japanese reducers is a durable re-sorting of the actuator choke or a one-session unwind.