Pairs Trading Strategy - Journal Guide
Pairs trading is a market-neutral strategy that simultaneously goes long one stock and short a correlated stock, profiting when their price relationship reverts.
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Stocks
Swing
Advanced
Entry & Exit Rules
Entry Rules
- Pair correlation above 0.80 over trailing 60 days
- Spread z-score exceeds 2.0 standard deviations
- No earnings or major catalyst for either stock within 5 days
- Both stocks are in the same sector or industry
Exit Rules
- Spread returns to the mean (z-score near 0)
- Stop-loss if z-score exceeds 3.5 standard deviations
- Time stop: exit if no convergence within 15 trading days
- Exit if correlation drops below 0.60
Key Metrics to Track
What to Record
Risk Management
Risk 1% per pair. Always maintain dollar-neutral positions (equal dollar amounts long and short) to eliminate market direction risk. Monitor for correlation breakdown, which is the primary risk. Avoid pairs trades around earnings dates as idiosyncratic risk spikes.
Common Mistakes
What Is Pairs Trading?
Pairs trading is a sophisticated strategy that profits from the relative performance of two correlated stocks. You go long the underperformer and short the outperformer, betting that their historical relationship will reassert itself.
The beauty is market neutrality. Whether the market goes up, down, or sideways, you profit as long as the spread between your two stocks converges.
The Statistical Foundation
Pairs trading is built on cointegration — the statistical property that two time series maintain a long-term equilibrium relationship even though each can wander independently.
Finding Cointegrated Pairs
- Screen for stocks in the same sector with similar business models
- Calculate rolling correlation (target > 0.80)
- Test for cointegration using statistical tests
- Measure the spread’s mean-reverting behavior
When to Enter
The spread z-score is your primary signal. When the spread stretches beyond 2 standard deviations from its mean, enter the trade expecting convergence.
Journaling Pairs Trades
Pairs trading requires tracking more variables than simple directional trades:
Position Details
Record both the long and short legs, including position size, entry prices, and the dollar-neutral ratio.
Spread Metrics
Log the z-score at entry and exit, the correlation coefficient, and the time to mean reversion. These are your key performance variables.
Risk Events
Track whether any pair experienced correlation breakdown and what caused it (earnings, sector rotation, M&A activity). This builds your risk awareness database.
Managing the Risks
The primary risk in pairs trading is correlation breakdown — when the historical relationship stops working:
- Earnings surprises can permanently change a stock’s relative value
- M&A activity removes one leg of the trade
- Regulatory changes can affect one company but not its pair
Your journal should flag any pairs trade where correlation dropped below 0.60, along with the cause. Over time, this tells you which risk factors to screen for before entering.
Position Sizing for Pairs
Always maintain dollar neutrality:
- If you buy $10,000 of Stock A, short $10,000 of Stock B
- Adjust for beta differences if needed
- Account for margin requirements on both legs
Your journal should track whether beta-adjusted sizing outperforms simple dollar-neutral sizing for your specific pairs.
How JournalPlus Helps
Strategy Tagging
Tag every trade with this strategy and track win rate, expectancy, and P&L by strategy over time.
Rule Compliance
Log whether you followed entry and exit rules. Spot when rule-breaking costs you money.
Performance Analytics
See which market conditions produce the best results for this strategy with automatic breakdowns.
Mistake Detection
AI flags pattern-breaking trades so you can stay disciplined and refine your edge.
What Traders Say
"Tracking correlation over time in my journal showed me which pairs were stable and which were breaking down. I avoided two major correlation breakdowns that would have cost me 5% each."
Frequently Asked Questions
How do I find good pairs to trade?
Start with stocks in the same sector or industry. Calculate their rolling 60-day correlation. Pairs with correlation above 0.80 that show mean-reverting spread behavior are candidates. Common pairs include Coca-Cola/Pepsi, Visa/Mastercard, and Goldman Sachs/Morgan Stanley.
What is a z-score in pairs trading?
The z-score measures how many standard deviations the current spread is from its historical mean. A z-score of 2.0 means the spread is 2 standard deviations from average, suggesting it's likely to revert. Most pairs traders enter at z-scores of 2.0 or higher.
Is pairs trading truly market-neutral?
In theory, yes -- you profit from the relative performance regardless of market direction. In practice, correlations can break down during market stress, creating directional exposure. That's why monitoring correlation in your journal is critical.
Start Tracking Your Trades
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