Tesla is planning to release self-driving taxis in June. Waymo has been scaling their self-driving taxi service for a while.
This market is to predict, between Waymo and Tesla, which company will first be responsible for a vehicle that is designed to be fully autonomous (i.e. operated with no driver behind the wheel, if there even is a wheel) and is available for public use causing a major accident. If the vehicle has a wheel, it must be operating without user input at the time of the crash.
A major accident must
Be reported on in at least two major news outlets, AND
Result in at least one fatality or one injury requiring hospitalization.
For a company's responsibility, either
The company admits primary wrongdoing, OR
The company is sued and found liable, OR
There is a settlement made that is publicly disclosed to involve the company giving some amount of money to another party. The amount of money need not be disclosed.
Once such a crash has met all these criteria and no other crashes from before that from the other company are pending litigation, the market will resolve to the company responsible for the crash.