Physical AI is the next bottleneck. Software stocks have already skyrocketed, but for humanoid robots to truly take off, the real sticking point is the 'actuator'—it accounts for 70% of the cost of a humanoid robot. Here are 4 U.S. stocks that each tackle different aspects of this Physical AI bottleneck: 1⃣ Novanta (NOVT) Specializes in the three most critical components inside actuators: motors, encoders, and torque sensors. High risk, but also high potential rewards. 2⃣ Moog Inc. (MOG-A) A veteran precision actuator manufacturer, driven by dual demand from defense and robotics. 3⃣ Timken (TKR) Focuses on bearings and motion control, the essential components needed for every joint in a robot. 4⃣ Vishay Precision Group (VPG) Produces precision sensors that allow robots to 'feel' force and position. Key logic: Jensen Huang said humanoid robots represent a $40 trillion market. But while everyone is chasing companies that make robots (Tesla Optimus, Figure AI), the real alpha lies in the component supply chain—just like how NVIDIA was the big winner during the AI chip boom. This time, the picks-and-shovels play is actuators. Software is no longer the bottleneck. The bottleneck for Physical AI lies in hardware: heat dissipation, power consumption, mechanical precision, and reliability. These companies are solving those problems.