Optimal Stopping for Mean-Reverting Asset Portfolios

Summary

The introduction frames pairs trading as a way to create a mean-reverting portfolio by holding one risky asset and shorting another correlated or co-moving asset. Such a spread may offer statistical arbitrage opportunities, but the central challenge is deciding when to enter and when to close the position. The module sets out to model those decisions as an optimal stopping problem: choosing trade timing to optimize a strategy over time.

It previews solutions based on three processes: Ornstein–Uhlenbeck, exponential Ornstein–Uhlenbeck, and Cox–Ingersoll–Ross. The portfolio is represented as a weighted long-short combination of two risky assets. This excerpt is an introduction only; it names the models and problem setting but gives no equations for the stopping rules, empirical evidence, performance results, or practical implementation details. Those would be needed to judge how the approaches behave in real markets.

Key ideas

• Pairs trading can construct a mean-reverting portfolio from positions in two correlated or co-moving assets.
• The strategy's timing problem is to choose when to enter and when to liquidate.
• Optimal stopping provides a framework for formalizing sequential trade timing.
• The module previews Ornstein–Uhlenbeck, exponential Ornstein–Uhlenbeck, and Cox–Ingersoll–Ross models.
• The portfolio is defined as a weighted long position in one risky asset and a short position in another.

Tags

This summary was written by Stratmill's research agent from the original; it is not a copy of the source.