Chapter 06

Systematic Trading Strategies

Systematic trading means executing trades based on predefined rules rather than gut feeling. You decide the rules in advance, then follow them without deviation. The data tells you what to do, and discipline keeps you executing.

Why Systematic Beats Discretionary

  • Consistency: A system takes the same trade every time the conditions are met — no second-guessing
  • Testability: You can test rules on historical data before risking real money
  • Scalability: A system can monitor hundreds of instruments simultaneously
  • Emotion removal: Rules don't panic in a crash or get greedy in a rally
A mediocre strategy executed with perfect discipline will outperform a brilliant strategy executed with poor discipline.

Strategy #1: Trend Following

The oldest and most proven systematic approach. The premise: prices that have been rising tend to continue rising, and prices that have been falling tend to continue falling.

How it works

  • Entry: Buy when price crosses above the 50-day moving average (or when the 20-day crosses above the 50-day)
  • Exit: Sell when price crosses below the 50-day moving average or when a trailing stop is hit
  • Sizing: Use ATR-based position sizing to equalize risk across positions

Trend following works best in markets that trend (commodities, currencies, some sectors). It struggles in choppy, range-bound markets where signals generate whipsaws.

Real-world example: A trend follower buys crude oil when it breaks above its 50-day moving average at $75. Sets a trailing stop at 2× ATR below. Oil runs to $95 over three months, trailing stop rises to $89. Oil pulls back to $88, stop hit — locks in $13 per barrel of profit.

Strategy #2: Mean Reversion

The opposite bet: prices that have moved too far from their average will snap back. Works best in large-cap stocks and indices that are fundamentally stable.

How it works

  • Entry: Buy when RSI drops below 30 (oversold) and price is near the lower Bollinger Band
  • Exit: Sell when RSI returns above 50 or price touches the middle Bollinger Band
  • Stop: Exit if price continues falling beyond a set ATR limit

Real-world example: A large-cap stock drops 8% in two days on no news, RSI hits 22, price is 2.5 standard deviations below its 20-day mean. You buy. Over the next week it recovers 5% as the panic fades. You exit as RSI crosses 50.

Strategy #3: Momentum

Buy recent winners, avoid or short recent losers. Distinct from trend following because you're ranking assets relative to each other rather than using absolute price levels.

How it works

  • Rank: Sort a universe of stocks by their 3–12 month returns
  • Buy the top: Hold the top 10–20% of performers
  • Rebalance: Repeat monthly or quarterly — sell losers, buy new winners

Momentum is one of the most documented anomalies in finance. It works across stocks, bonds, currencies, and commodities. The risk: momentum crashes when trends suddenly reverse (e.g., March 2009).

Strategy #4: Pairs Trading

Find two stocks that historically move together. When they diverge, bet on convergence — buy the laggard, short the leader.

How it works

  • Find a pair: Two stocks in the same sector with a strong historical correlation (e.g., Coca-Cola and Pepsi)
  • Track the spread: Monitor the price ratio or difference between them
  • Trade divergence: When the spread widens to 2+ standard deviations, go long the cheap one and short the expensive one
  • Close on convergence: Exit when the spread normalizes

Pairs trading is market-neutral — you profit whether the market goes up or down, as long as the spread converges. The risk: sometimes spreads diverge for fundamental reasons (one company genuinely deteriorates) and never converge back.

Strategy #5: Breakout Trading

Enter when price breaks out of a defined range, betting that the breakout signals the start of a new trend.

  • Identify the range: A stock trading between $48 and $52 for 3 weeks
  • Entry: Buy when price closes above $52 on above-average volume
  • Stop: Set stop at the midpoint of the range ($50) or just below the breakout level
  • Target: Measure the range height ($4) and add it to the breakout point ($52 + $4 = $56)

Volume confirmation is critical. A breakout on low volume often fails (false breakout). A breakout on 2–3× average volume has much higher follow-through.

Building Your Trading System

Every systematic strategy needs these components:

  1. Universe: Which instruments do you trade? S&P 500 stocks? Futures? Forex? Narrower universes are easier to manage.
  2. Signal: What triggers a trade? Moving average cross, RSI extreme, breakout with volume — be specific.
  3. Entry rules: Exactly when and how do you enter? At the close? On a limit order? At market open?
  4. Position sizing: How much capital per trade? Fixed percentage risk or volatility-based sizing?
  5. Exit rules: Stop loss, profit target, trailing stop, time stop — define all of them before you trade.
  6. Review process: How often do you evaluate performance and refine the system?

Common Pitfalls

  • Overfitting: Testing thousands of rule combinations until one “works” on past data. If your rules are too specific, they won't work in the future.
  • Ignoring costs: Commissions, slippage, and spread add up fast, especially in high-frequency strategies
  • Survivorship bias: Testing only on stocks that still exist today. The ones that went bankrupt are missing from your data.
  • Curve fitting: Optimizing parameters to perfectly match historical data. True edge comes from simple, robust rules.
  • Abandoning the system: Switching strategies after a few losses. Every system has losing streaks. Trust the process if the logic is sound.
The best trading systems are simple. If you can't explain your strategy in two sentences, it's probably too complex. Complexity is the enemy of robustness.

Where to Go from Here

You now have a solid foundation in quantitative trading — from understanding market data and signals to building portfolios, managing risk, and deploying systematic strategies. The next step is practice:

  • Pick one strategy type that resonates with your style
  • Paper trade it for at least 3 months before using real money
  • Track every trade in a journal — entries, exits, reasons, emotions
  • Review performance monthly and refine your rules
  • Start with small position sizes — your first goal is survival, not profit

Remember: the quant advantage isn't about finding a magic formula. It's about making decisions based on data instead of emotions, managing risk ruthlessly, and executing with discipline over hundreds of trades.