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Finaxion Research · The Turtles: 55-day breakout · single stocks · Recomputed 2026-09-10

Does the Turtles: 55-day breakout work on FLEX?

The Turtles: 55-day breakout does not beat buy-and-hold on FLEX: -10.7 points a year over 32 years.

Total return
225.7%
Buy and hold
×80
CAGR
3.7%
Sharpe
0.13
Max drawdown
-79.5%
Trades
132
Out of sample
overfit
Years
32
1×10×100×108×19951998200120042007201020132016201920222025
StrategyFLEX

Findings

  1. The Turtles: 55-day breakout does not beat buy-and-hold on FLEX: -10.7 points a year over 32 years.
  2. Against the S&P 500 over the same window: -7.2 points a year.
  3. Total return +225.7% versus ×80 for buy-and-hold, with 132 trades.
  4. The result does not hold out of sample: it is overfit.
  5. Maximum drawdown -79.5%.
  6. It beats in neither half of the history (split at 2010).
  7. It ranks #108 of 235 markets for this strategy by annual excess over the S&P 500.

Findings derived from the full panel. Each carries its number and its denominator; the computations are reproducible with artifact 0712690e8935.

Exactly what was tested

Close above the prior 55-day high → entry. Close below the prior 20-day low → exit (original System 2). No pyramiding or ATR sizing: we test the signal alone.

How to read it

The verdict compares the strategy with buying and holding FLEX over the same window, with round-trip costs per asset class. “Out of sample” is walk-forward: the rule is fit on one stretch and judged on the next. A result that beats in the full sample but not out of it is overfit. Full methodology in the protocol. How we test.

Open this backtest with its trades   Trades (CSV)

Every strategy on FLEX → · Full page for The Turtles: 55-day breakout →

How to cite

Finaxion Research (2026). Does the Turtles: 55-day breakout work on FLEX?. Daily backtest 1962-01-01–2026-08-31, artifact 0712690e8935. https://finaxion.app/en/research/donchian-55-breakout/flex

Not a recommendation. Past performance does not guarantee future results.