Quant interview prep guides

Market Making Probability Estimation Interview

Market making probability estimation interview guide for converting probabilities into fair values, updating signals, and comparing implied prices.

Candidates quoting binary or event-based markets.

Probability can be fair value

For a binary payoff that pays 100 if an event happens, a 37 percent probability estimate maps to a simple fair value of 37.

Calibrate before quoting

A market-making answer is stronger when you admit uncertainty in the probability estimate and choose a spread that reflects that uncertainty.

Concrete example

If you estimate a 60 percent chance of an event that pays 1, the fair value is 0.60 before fees, spread, or risk adjustment.

Update with signals

A new signal can change the probability estimate. Explain whether the signal is strong enough to move fair value or only widen the spread.

Compare to implied probability

If a quote implies 45 percent and your estimate is 55 percent, the difference may be edge, but only after considering uncertainty and costs.

Common mistakes

Candidates often quote a probability without saying how confident they are. In market making, confidence affects spread width.

Practice the pattern

Use the LeetQuidity curriculum and calibration to turn this topic into a focused practice plan.