Strategy Recap
Donchian breakout is one of the oldest trend-following frameworks in systematic trading. The logic is deliberately mechanical: buy any position in the 24-stock universe when it closes at a new 20-day high; exit when it closes at a new 20-day low. No macro overlay, no sentiment filter — just price action expressing momentum. The universe spans large-cap US equities across tech, financials, healthcare, consumer staples, and energy, giving the engine a broad canvas to find trending names.
Backtest Baseline
Over the full 451-day backtest window the strategy returned +6.95% on a starting equity of roughly $10,000, finishing at $10,695. Annualised that is a 3.83% CAGR — uninspiring on its own, though not the headline number that matters most here.
The concern is the Sharpe of 0.34 paired with a 21.73% max drawdown. That ratio of pain to gain is hard to justify against a passive alternative. Turnover clocked in at over 2,000%, meaning the portfolio churned more than 20× its notional value across 108 trades — each carrying a flat $1 fee, so friction is contained, but slippage risk on real fills in less liquid names would compound the drag. The win rate of 38.46% is typical for breakout systems — they win infrequently but need their winners to run far — so the low rate alone is not alarming, but it does demand patience from any allocator.
Fold Analysis: A Tale of Two Regimes
The walk-forward cross-validation splits the history into four equal-length folds, and the picture is uneven:
| Fold | Period | Return | Sharpe | Max DD |
|---|---|---|---|---|
| 1 | Aug 2024 – Jan 2025 | +0.73% | 0.21 | 6.71% |
| 2 | Jan 2025 – Jul 2025 | −7.46% | −1.07 | 15.58% |
| 3 | Jul 2025 – Dec 2025 | +14.09% | 2.72 | 3.14% |
| 4 | Dec 2025 – May 2026 | +11.35% | 1.86 | 6.01% |
Fold 2 is the red flag: a −7.46% return with a −1.07 Sharpe suggests the strategy ran into a choppy, range-bound market where breakout signals fired repeatedly into reversals. Folds 3 and 4, however, tell a meaningfully different story — the combination of double-digit returns and Sharpe ratios above 1.5 indicates the system found genuine trending conditions and rode them cleanly.
Validation Verdict
The platform's automated validation gate returned failed, driven primarily by a low Probabilistic Sharpe Ratio (PSR) of 0.674 and a Deflated Sharpe Ratio (DSR) of 0.198. With only six trials in the optimisation space the multiple-testing haircut is moderate, but the underlying signal is simply not strong enough to clear the bar. Three of four folds finishing positive is encouraging; one sharply negative fold is enough to suppress confidence at the required statistical threshold.
The out-of-sample Sharpe of 1.86 (fold 4, the most recent period) is the strongest counter-argument. Recency is not always representative, but a strategy improving as its universe matures into trending conditions is at least doing the right things mechanically.
Recent Live Activity
Through the first two weeks of June 2026 the strategy has been active and deliberate. Buys in AAPL, MSFT, ABBV, and CAT were entered across June 2–4; the MSFT position was subsequently sold on June 9 and replaced with a UNH long — consistent with the exit-on-20-day-low rule triggering a rotation. Portfolio value has ranged between roughly $9,650 and $9,950, with cash hovering around $1,200–$2,000 after the latest reallocation. A handful of rejected signals on June 5 and June 8 suggest the position-sizing guard rails are working as intended.
Bottom Line
Donchian breakout is a structurally sound mechanical strategy that rewards patience. Its recent form — two consecutive folds with Sharpe above 1.8 — merits continued monitoring. The failed validation gate, a maximum drawdown north of 20%, and fold 2's rough patch are honest reminders that trend-following strategies can endure extended dead zones before the next trending regime arrives. Worth watching; not yet worth scaling.