Learn to update, not to recite
Start with arithmetic you can trust, then conditional probability and expectation. Add spreads, inventory, adverse selection and options payoffs once those foundations are reliable. A fast answer based on an unstated assumption is weaker than a careful answer that survives a follow-up.
Jane Street’s official guidance describes collaborative problem solving and lists probability, statistics, coding and data analysis among possible topics. This is one employer’s guidance, not a universal syllabus.
A trading question has three layers
An asset pays 20 with probability 0.4 and zero otherwise. Its expectation is 8. Quoting 7–9 does not guarantee profit: a customer may know the outcome. After a customer buys, ask what that trade tells you before repeating the quote.
The number is layer one. The information assumption is layer two. Position size and inventory are layer three. The market-making lab makes those consequences visible.
A weekly loop
- Continue the next path lesson on four days.
- Retrieve yesterday’s mistakes before reading the method.
- Run one strict mock and explain the weakest answers aloud.
- Run a market simulation and inspect the entire inventory path.
Scope and limits
Ask your recruiter about current tools and timing. Numeric practice cannot replace a conversation, your project knowledge or actual programming. The Trader profile adjusts emphasis without hiding fundamentals.
Try a fresh question
This optional exercise uses the actual parameterized bank.
Worked method
Keep the practice connected
Train Probability · Follow the Quant Path · Evidence standard