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Optiver·Software Engineer·Technical Phone Screen·Intermediate

Intermediate
Jul 2026

Summary

Optiver software engineer interview with a pretty involved quant/systems question that blurred the line between coding and strategy design. One question but it had a lot of moving parts and I'm still not sure I handled all of them well.

Questions Asked (1)

Q1

Given minute-level OHLCV data for a single stock across 180 trading days, design and backtest a mean-reversion strategy. Cover entry and exit rules, risk controls, position sizing, transaction costs, and slippage. Your backtest should output PnL, win rate, average trade return, max drawdown, volatility, Sharpe ratio, and turnover. Then do a hold-out or walk-forward validation and discuss overfitting, using a statistical test like bootstrap or a reality-check procedure to assess whether the results are actually significant.

System DesignTechnical Trade-offsA/B Testing & Experimentation
Author's notes

This was a lot to unpack in one question.

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AI HintsAI Generated

Suggested Approach

Start by framing the problem as a full research pipeline: hypothesis, data handling, strategy rules, backtest engine with realistic costs, performance metrics, and validation. Emphasize that mean reversion on minute bars requires careful treatment of microstructure noise and that validation is critical to avoid overfitting. Conclude with a statistical test to assess significance and discuss limitations.

Pro tip: Optiver values rigorous, production-quality backtesting: mention that you would use event-driven simulation with order book dynamics, and that you'd test the strategy's sensitivity to parameter perturbations and execution latency.

1. Define Hypothesis and Data Preparation

State the mean-reversion hypothesis (e.g., short-term price dislocations revert) and describe data cleaning: handle missing bars, adjust for splits/dividends, and compute returns or z-scores over a lookback window.

2. Specify Entry/Exit Rules and Risk Controls

Define entry when price deviates by k standard deviations from a moving average, exit on reversion to mean or after a fixed holding period. Include stop-loss, take-profit, and time-based exits to control risk.

3. Position Sizing and Cost Modeling

Use volatility-based sizing (e.g., target constant risk) and cap exposure. Model transaction costs (commission, fees) and slippage (e.g., fixed bps or volume-dependent) to reflect realistic execution.

4. Backtest and Compute Metrics

Implement an event-driven backtest that processes minute bars sequentially. Calculate PnL, win rate, average trade return, max drawdown, volatility, Sharpe ratio, and turnover.

5. Validation and Statistical Significance

Split data into in-sample and out-of-sample (hold-out) or use walk-forward analysis. Apply a bootstrap or reality-check procedure (e.g., White's Reality Check) to test if performance is statistically significant and discuss overfitting risks.

Key Points to Mention

  • Mean reversion hypothesis and rationale for minute-level data
  • Entry/exit rules with clear thresholds and risk controls (stop-loss, take-profit)
  • Position sizing based on volatility targeting and capital constraints
  • Transaction cost and slippage modeling (e.g., fixed bps, volume-based)
  • Performance metrics: Sharpe ratio, max drawdown, turnover, win rate
  • Validation techniques: walk-forward, hold-out, bootstrap, reality check
  • Overfitting mitigation: parameter stability, out-of-sample testing, avoiding data snooping

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.