Quant Interview Question: Trading Strategy
You've been given access to a large dataset containing daily closing prices for a variety of stocks over the past 10 years.
1. Describe a basic trading strategy you might derive from this data.
2. What kind of statistical or machine learning techniques would you consider using to validate or optimize this strategy?
3. Imagine after implementing your strategy, for three consecutive months, it performs significantly below expectations. What steps would you take to investigate and adjust your approach?
4. How would you factor in transaction costs, taxes, or other real-world considerations when evaluating the profitability of your strategy?
Quant Interview Answer: Trading Strategy
1. Basic Trading Strategy:
A simple approach is the Moving Average Crossover. This strategy uses two moving averages: a short-term (e.g., 50 days) and a long-term (e.g., 200 days). The basic concept is:
- Buy Signal: When the short-term moving average crosses above the long-term moving average.
- Sell Signal: When the short-term moving average crosses below the long-term moving average.
2. Statistical/Machine Learning Techniques:
- Backtesting: It's essential to test the strategy on historical data before deploying to gauge its historical performance.
- Cross-validation: This prevents overfitting, especially if making adjustments based on backtesting results.
- Machine Learning: Regression techniques like Random Forests or Gradient Boosting Machines could be used to predict price changes, while classification techniques can predict the direction of change. Deep learning models, such as LSTM networks, are suitable for time series forecasting.
- Sharpe Ratio and Maximum Drawdown: These metrics can help evaluate the risk-adjusted performance and worst-case scenario of the strategy, respectively.
3. Three Months of Underperformance:
- Review Market Conditions: It's vital to consider major economic or geopolitical events that might have affected stock prices.
- Model Diagnostics: Ensure the model's assumptions are still valid and check for any "regime change" in the market dynamics.
- Revalidation: It's a good idea to retest the strategy using fresh data to ensure its continued relevance.
- Adaptation: The strategy might need refining, or even a complete change based on new findings or market conditions.
4. Real-world Considerations:
- Transaction Costs: Ensure that brokerage fees and other transaction-related costs are subtracted from each trade's profit/loss.
- Taxes: Capital gains tax could significantly impact net profitability, especially for trades held for a short duration.
- Slippage: Real-world trading may result in order execution at prices different from what was expected due to market factors.
- Liquidity: It's essential to choose stocks that can be easily traded without causing significant price changes.
- Leverage: While it can increase profits, it also increases potential losses. It's essential to consider the cost of borrowing and the increased risk.
Remember, historical performance doesn't guarantee future results. It's vital to review and adjust trading strategies regularly.