Thesis
The mean-reversion strategy applies one of the oldest systematic edges in equity markets: when a stock becomes statistically oversold (RSI below 30), expect a snap-back; when overbought (RSI above 70), take profit. Applied across a 24-stock universe of large-cap US names — spanning technology, financials, healthcare, consumer staples, and energy — the approach keeps concentration risk manageable and sidesteps the liquidity tail-risk of smaller names.
Backtest Performance
Over 451 days of historical simulation, the strategy generated a 14.73% total return (7.98% annualised CAGR) across 38 trades, with a win rate of 70.59% and a Sharpe ratio of 0.58. Maximum drawdown reached 15.64%. Turnover ran high at 879%, reflecting the strategy's tendency to rotate in and out of positions as RSI signals fire. Fee drag was minimal at $38 total ($1 flat per trade), with no FX costs given the all-USD universe.
Walk-Forward Validation: A Cautionary Signal
The strategy did not pass Headmars' walk-forward validation gate. The four-fold cross-validation tells a revealing story:
| Fold | Period | Return | Sharpe | Max DD |
|---|---|---|---|---|
| 1 | Aug 2024 – Jan 2025 | +2.06% | 0.57 | 4.24% |
| 2 | Jan 2025 – Jul 2025 | +11.10% | 1.32 | 10.53% |
| 3 | Jul 2025 – Dec 2025 | +2.21% | 0.46 | 8.80% |
| 4 | Dec 2025 – May 2026 | −2.84% | −0.33 | 14.96% |
Fold 2 is the outlier that flatters the aggregate figures. The remaining three folds average a near-zero return with worsening drawdown. The most recent out-of-sample fold — the only period the model had never "seen" — lost 2.84% against a nearly 15% maximum drawdown. The probabilistic Sharpe ratio (PSR) of 0.785 leaves a meaningful probability that the observed edge is noise, and the deflated Sharpe ratio (DSR) of 0.304, adjusted across six trials, reinforces that concern.
Recent Activity
The live paper-trading account is currently idle. Daily runs from June 18 through June 25 produced zero executed trades, with portfolio value oscillating between $10,031 and $10,083 against a $7,569 cash balance. The last executed trade was a buy of 21 shares of WMT at $115.75 on May 31 — a textbook oversold entry into a defensive consumer-staples name.
The absence of signals is itself informative: the 24-stock universe is not reaching RSI extremes in either direction right now. For a pure mean-reversion system, a mid-RSI, range-bound tape is simply dead air.
Strengths and Risks
Strengths. A 70%+ win rate is genuinely encouraging and consistent with the academic literature on RSI-based mean reversion in large-cap equities. The strategy is transparent, fully rule-based, and straightforward to audit.
Risks. The validation failure is the central concern. One strong fold accounts for the bulk of aggregate returns, and the most recent out-of-sample period was negative. High turnover could amplify fee and spread drag in a live account with real market impact. The binary RSI threshold (30/70) is also a known limitation — it does not adapt to volatility regimes, meaning the same reading carries different implications in a calm tape versus a high-VIX environment.
Outlook
Mean-reversion remains on the active watchlist, but its validation failure warrants deeper investigation before any capital scaling. The immediate priority is understanding whether Fold 2's outperformance was regime-specific — likely a volatile recovery period where oversold bounces were unusually reliable — and whether adding a volatility filter would stabilise out-of-sample results. Until a subsequent validation window shows positive out-of-sample returns, the strategy earns observation status, not deployment approval.