What is a Paired Trade? Definition, Execution, and Example
A paired trade is a market-neutral strategy that takes offsetting long and short positions in two correlated securities to profit from the convergence or divergence of their price relationship.
What is a paired trade?
A paired trade, also known as pairs trading, is a market-neutral strategy in which a trader simultaneously buys one security and sells short a related security. The two securities are selected because they historically move together due to similar business models, sector exposure, or macroeconomic drivers. The trader profits when the price spread between the two instruments reverts to its historical average after diverging. Because the long and short positions offset much of the broad market risk, the strategy seeks to generate returns from relative price movement rather than from the direction of the overall market.
How a paired trade is identified
The trader selects two securities with a high historical correlation, typically measured over a lookback period such as 60 or 120 days. The price ratio is calculated as:
Price Ratio = Price of Security A / Price of Security B
The trader then computes the mean and standard deviation of this ratio over the lookback period. A trade is initiated when the ratio deviates from its mean by a set number of standard deviations, commonly two. If the ratio is above the mean, the trader sells short Security A and buys Security B. If the ratio is below the mean, the trader buys Security A and sells short Security B. The position is closed when the ratio returns to the mean or hits a predetermined stop-loss level.
Position sizing is often adjusted so that the dollar value of the long leg equals the dollar value of the short leg, creating a beta-neutral or dollar-neutral exposure.
Worked example
PepsiCo trades at 180 and Coca-Cola trades at 60. The price ratio PEP / KO equals 3.00. Over the past 90 trading days, the average ratio has been 2.90 with a standard deviation of 0.08. The current ratio of 3.00 is 1.25 standard deviations above the mean, which does not yet trigger a trade.
Two days later, PEP rises to 186 while KO falls to 58. The new ratio is 186 / 58 = 3.21, which is 3.88 standard deviations above the mean. The trader sells short 100 shares of PEP for $18,600 and buys 310 shares of KO for $17,980, adjusting for near dollar neutrality. If the ratio later reverts to 3.00, the trader closes both legs and profits from the convergence, minus borrow costs, commissions, and slippage.
When traders use it
Paired trades are used when traders expect two historically correlated securities to diverge temporarily due to idiosyncratic news, liquidity shocks, or sector rotation. The strategy is common in equities, ETFs, commodities, and futures. It is frequently employed around earnings announcements when one stock in a sector moves sharply on company-specific news while its peer does not. Traders monitor the z-score of the price ratio to time entries and exits, and they use stop-losses to manage the risk that the divergence persists or widens. market-neutral strategy
Limitations and common misconceptions
Pairs trading is not risk-free. Correlation can break down permanently due to fundamental changes in one company, such as a bankruptcy, merger, or regulatory action. The spread can diverge far beyond historical norms, forcing the trader to either book a loss or maintain margin-intensive short positions. Short borrow costs and availability can erode profits, especially for hard-to-borrow securities. The strategy does not eliminate market risk entirely; if both securities move sharply in the same direction, the dollar-neutral position may still experience mark-to-market volatility.