Quant interview prep guides

Market Making vs Probability Interviews

How probability interview skills connect to market-making quotes, fair prices, spread decisions, signal updates, and risk communication.

Candidates who know probability methods but struggle to convert them into trading-game decisions.

Probability becomes price

For binary events, a probability estimate can become a price. If an event is worth 100 when true and 0 when false, 60 percent probability implies fair value near 60.

Uncertainty still matters

A probability estimate can be rough. The quote should show whether the estimate is precise, noisy, or vulnerable to new information.

Concrete example

If you estimate a 55 percent chance but the signal is weak, quoting 51 at 59 may make more sense than quoting 54.9 at 55.1.

Updates are central

Market-making rounds often add trades, signals, or related-market moves. Each one can change probability, uncertainty, or inventory pressure.

Common mistakes

Candidates often stop after the probability calculation. In a quote-based interview, say the fair price, spread, and what information would move it.

Practice the pattern

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