RealTest SPX Mean-Reversion

Mean-Reversion Methodology

This strategy measures the velocity and magnitude of price decline in S&P 500 constituents relative to their recent trading range. When a stock reaches a statistically defined oversold threshold, it generates a limit order entry. The logic is designed around the empirical observation that large-cap equities tend to revert after sharp short-term dislocations, particularly when the decline is driven by broad market sentiment rather than company-specific events.

Execution and Liquidity

Entries use calculated limit orders rather than market orders, which serves two purposes: it improves average fill price and naturally filters for the deepest oversold conditions. The S&P 500 universe ensures sufficient liquidity for realistic execution at the modeled prices. Backtests include Interactive Brokers tiered commissions and a limit order buffer to account for real-world fill dynamics.

Portfolio Context

Mean-reversion strategies tend to exhibit low correlation with trend-following and momentum systems. Adding this type of strategy to a portfolio that already holds long-term or momentum-based positions can reduce overall equity curve volatility. The strategy is most active during elevated-volatility regimes, providing returns in the periods where buy-and-hold exposure typically suffers the largest drawdowns.