A SpaceX takeover of Tesla is a live possibility if Tesla stock falls hard, which would be bad for Tesla shareholders and good for Musk, who controls SpaceX.

• The setup: if Tesla's stock drops sharply while SpaceX holds steady or rises, SpaceX could buy Tesla outright.
• A trigger could be a setback on Optimus robots or Full Self-Driving, such as a deadly robotaxi crash, hitting at the same time.
• Musk would likely give up his Tesla stock pay package, but he doesn't need it because he holds 80% voting control of SpaceX.
• There is no timeline; it's an option Musk can pull only if Tesla stumbles.

Outlook: No merger is imminent, but a big Tesla stumble would make a SpaceX buyout far more likely.