The Hot Path
Nothing is scripted. The workload is drawn, the cost model is real, and the best answer changes every interval.
The brief
You own the latency budget of a trading system for one day. Each interval is a component — the ingest buffer, the order map, the book's price levels, the top-k signal scan, the covariance step, the P&L accumulator, the parallel reduction — and for each one you choose a specification and set one number: a capacity, a tick range, a value of k, a thread count. Then a cost model charges you for the operations your choice performs and for the memory stalls they incur at whatever cache level your working set actually landed in. A hash map is right until the data leaves cache. An array by tick is right until the range is wide. Kahan summation is right only when the precision requirement asks for it. Every one of those depends on numbers you are shown, and they change.
How you play it
Specify a trading system component by component against a drawn workload, and a cost model charges you for the operations and the cache misses your choices actually cost.
The job: Quant developer — Turning research into something that runs — correctly, fast enough, and the same way twice.
What a quant developer actually does →What you're judged on
Every decision is marked to market server-side. These are the meters that move — run one to zero and the simulation ends there.
What it tests
No trivia — the simulation only asks what the chair actually has to know.
Where you learn this
The Hot Path is the finale of Runtime Row, waiting past Level 24 — The Final Review. You can sit down right now and find out how much of it you already know; the course is there for the parts you don't.
Play Runtime Row →Other chairs
The Weekend
Sixty-two hours to Tokyo's open. You cannot save everyone — and one of them you cannot lose.
The Structurer
Every note is a bond plus options. Pick the wrong shape and the client finds out at maturity.
The President
Every policy has two halves: what you do, and who pays. The bond market grades the second one.
The Fund
Your product is returns. Your business is assets. They want opposite things.
The First Year
Twelve months on your own. No perfect month — only wiser and poorer ones.
The Newsroom
One shift on the data desk. Every story is a stats trap in disguise.
Mission Control
No options to pick — do the math, key in the number, bring them home.
The Policy Chair
You are the central bank. One rate, every quarter, a whole economy on the line.
The CFO's Chair
You run the firm's capital. Ten board meetings, one question every time: where does the cash go?
The Pit
You run the book. The tape moves, the Greeks bite, margin is real. Survive the session.
Your Own Worst Enemy
The market can't hurt you. You can. Ten moments, one enemy — the one making the decisions.
The Quote
Your quote is two numbers. Everything that happens next is arithmetic.
The Opponent
Nothing here is scripted. They are running a model of you, and it updates.
The Desk
Run a derivatives desk for one week — it does not stay calm.
Rotation Day
Ten desks, one stack of cards each. Sort them right — and never, ever misfile ethics.
The Expert Witness
Ten regression tables enter evidence. The significant one is usually the trap.
The War Room
The VaR says you're fine. The tail says otherwise. Ten audits — read which one is lying.