Perception silicon and precision gears led while the battery-and-power chokepoint sold off, with Ambarella out front and Enovix the sharpest decliner.

The session rewarded the chokepoints that turn a humanoid into a working machine and punished the ones that power it. Ambarella (AMBA) rose 8.4% to $68.80 on the edge-AI-compute chokepoint, extending its post-earnings run — a record fiscal-Q2 on edge-AI and automotive strength, reported Sept 3 — and reinforced by a Citi Global TMT Conference appearance pitching a physical-AI story. On this vertical AMBA is the perception-and-inference silicon that lets a robot see and act at the edge, and it was the basket's clear leader. The precision-mechanics layer firmed alongside it: the Nabtesco ADR (NCTKY) added 4.1% to $14.63 on the precision-gears chokepoint — the RV-reducer supply that every industrial arm depends on — and Teradyne (TER) rose 3.1% to $383.69 on the test-and-integration line.

The laggard was Enovix (ENVX), down 8.9% to $3.16 on the batteries-power chokepoint — the same name that led the drone basket lower, on the same continued unwind of its post-leadership-change overhang, with no fresh company news. The energy chokepoint that sets a humanoid's runtime was the day's weakest link.

The weakness clustered in power and the speculative platform names. Amprius (AMPX) fell 5.0% to $9.87 and Ultralife (ULBI) dropped 5.2% to $5.63 on the same batteries-power chokepoint, Serve Robotics (SERV) lost 5.0% to $4.66 on the platforms-integrators line, and the Nidec ADR (NJDCY) fell 4.6% on motors. The read is a rotation within the vertical: capital paid up for the perception silicon and the irreplaceable gear-and-reducer suppliers, where the demand thesis is concrete, and sold the battery and pre-revenue platform names where it is not yet.

The catalyst calendar is a fall story. ABB's robotics divestiture to SoftBank is expected to close by late 2026, a consolidation of one of the largest industrial-arm franchises. On the humanoid side, NVIDIA's Isaac GR00T reference design is slated to ship from Unitree late this year, and RoboBusiness (Oct 19–21, Santa Clara) carries a humanoid-for-industry track that should set the near-term roadmap. Company prints follow — Hyundai's Q3 on Oct 27, Timken on Oct 30, Schaeffler's nine-month results Nov 10 — and the rare-earth-magnet clock behind every motor and actuator ticks toward China's Nov 10 export-control suspension expiry.