Quantitative Finance Interview Prep for Singapore Students

Quantitative Finance Interview Prep for Singapore Students

Quantitative finance firms are among the highest-paying internship destinations globally — and they recruit selectively in Singapore, primarily from the mathematics, statistics, physics, and computer science departments of NUS, NTU, and to a lesser extent SMU. This guide prepares you for the full spectrum of quant interview content.

The Quant Finance Landscape in Singapore

Firms recruiting quant interns in Singapore or for Singapore-based roles include:

• Jane Street — Equity and FX trading, options market making; recruits NUS/NTU maths and CS students for their prop trading internship (highly competitive)
• Optiver — Options and derivatives trading; small Singapore presence but recruits from top SG universities
• DRW, Jump Trading, Two Sigma, DE Shaw — Various degrees of Singapore presence for trading, research, and tech roles
• Quantitative teams within banks — Goldman Sachs Strats, JP Morgan Quantitative Research, Deutsche Bank XVA, UBS Quantitative Finance — all based in Singapore

Probability and Brain Teasers

Probability questions are the most distinctive component of quant finance interviews and the hardest to prepare for without deliberate practice.

Core probability concepts to master:

Conditional probability (Bayes' theorem) P(A|B) = P(B|A) × P(A) / P(B)

Classic problem: "I have two children. At least one is a boy. What is the probability the other is a boy?" Answer: The sample space of two-child families with at least one boy is {BB, BG, GB}. Only one outcome (BB) has both boys. Answer: 1/3.

Expected value E[X] = Σ x × P(X=x)

Classic problem: "You roll a six-sided die and receive £ equal to the number rolled. What would you pay to play this game?" E[X] = (1+2+3+4+5+6)/6 = 3.5. You should pay up to £3.5.

Geometric / negative binomial distributions "What is the expected number of coin flips to get two heads in a row?" Answer: 6 (derive using states and expected value equations)

Birthday problem variants "How many people need to be in a room for there to be a 50% chance that two share a birthday?" Answer: ~23 people. Know the formula: P(no match) = 365/365 × 364/365 × 363/365 × ... and solve for when this drops below 0.5.

Brain Teasers

Classic types:

"You have 12 balls, one of which is heavier or lighter than the others. You have a balance scale. What is the minimum number of weighings needed to identify the odd ball and whether it is heavier or lighter?" Answer: 3 weighings.

"A factory has 10 machines. Nine produce 1kg balls. One produces 1.1kg balls. You have a digital scale (not a balance) and can weigh once. How do you identify the defective machine?" Answer: Take 1 ball from machine 1, 2 from machine 2, etc. Weigh all 55. The expected weight if all machines worked correctly is 55kg. If the actual weight is 55.X kg, machine X is defective (because you took X balls from it, each 0.1kg heavy).

Options Pricing: Key Concepts

Black-Scholes intuition — The price of a European call option is determined by: current stock price (S), strike price (K), risk-free rate (r), volatility (σ), and time to expiry (T). C = S·N(d1) - K·e^(-rT)·N(d2). Know what each term represents conceptually.

The Greeks:

• Delta (Δ): Change in option price per £1 change in underlying. Call delta: 0–1. Put delta: -1–0.
• Gamma (Γ): Rate of change of delta. High gamma near expiry and near-the-money.
• Theta (Θ): Time decay. Long options lose value as time passes (negative theta).
• Vega (ν): Change in option price per 1% change in implied volatility.
• Rho (ρ): Change in option price per 1% change in interest rate.

Put-call parity: C - P = S - K·e^(-rT). Know this and be able to explain what happens if it is violated (arbitrage opportunity).

Mental Arithmetic

Quant interviews test arithmetic speed. Common categories:

• Percentage calculations: "What is 17% of 340?" (340 × 0.17 = 57.8)
• Probability multiplication: "Two independent events each have probability 0.4. What is the probability at least one occurs?" (1 - 0.6² = 1 - 0.36 = 0.64)
• Option payoff: "A call with strike 50 on a stock trading at 67 — what is the intrinsic value?" (67 - 50 = 17)

Practise mental arithmetic daily for 4–6 weeks before your interview using apps like Mental Math or timed Anki decks.

Stochastic Calculus: Entry Level

For more advanced quant roles (research, derivatives pricing), you may encounter:

Brownian motion: A continuous-time random process with independent increments, normally distributed with mean 0 and variance t. Used to model stock prices.

Itô's Lemma: If X follows a diffusion process dX = μdt + σdW, and Y = f(X,t), then: dY = (∂f/∂t + μ∂f/∂X + ½σ²∂²f/∂X²)dt + σ∂f/∂X dW

This is the foundation of Black-Scholes derivation. Know the conceptual purpose even if the derivation is complex.

Singapore-Specific Prep

For Jane Street and Optiver roles in Singapore, the interview process typically includes:

1. Online aptitude test (probability, mental maths, logical reasoning — 30–60 minutes, timed)
2. Phone/video technical interview (probability, brain teasers, options concepts)
3. Final round (in-person or virtual — multiple rounds, trading games, full technical assessment)

Jane Street also runs a FLOW internship programme for earlier-year students with potential but less experience — this is a less competitive entry point.

The NUS Department of Mathematics and NTU School of Physical and Mathematical Sciences run problem-solving societies with regular quant puzzle sessions — engage with these communities as early as possible.