Mean reversion · daily rule · Energy & power
Bollinger Reversion on Fluence Energy
What the play says
FLNC with the play, last two years
Shading shows the play's call from the close that triggered it.
Growth of $10,000 since 2021
Log scale. After trading costs, with T-bill interest while out.
The record
The play against buying and holding FLNC over exactly the same dates, after costs.
| Play, since 2021 | Hold, since 2021 | Play, 5 yrs | Hold, 5 yrs | |
|---|---|---|---|---|
| Annual return | −17.4% | −28.4% | −17.4% | −28.4% |
| Total return | −61% | −80% | −61% | −80% |
| Worst drawdown | −78.4% | −90.0% | −78.4% | −90.0% |
| Volatility | 51.6% | 98.1% | 51.6% | 98.1% |
| Sharpe ratio | −0.17 | 0.11 | −0.17 | 0.11 |
| Time invested | 31% | 100% | ||
| Switches per year | 9.7 | 0 |
Every call, graded
Right on 34 of 47 closed calls (72%). In calls averaged −0.2%; out calls saw FLNC move +2.6% on average.
| Called | Call | Price | Until | FLNC moved | Result |
|---|---|---|---|---|---|
| Sep 17, 2026 | IN | $7.66 | now | −11.5% | open |
| Aug 3, 2026 | OUT | $14.56 | Sep 17, 2026 | −47.4% | ✓ right |
| Jul 29, 2026 | IN | $11.89 | Aug 3, 2026 | +22.5% | ✓ right |
| May 6, 2026 | OUT | $13.56 | Jul 29, 2026 | −12.3% | ✓ right |
| Apr 29, 2026 | IN | $11.83 | May 6, 2026 | +14.6% | ✓ right |
| Apr 14, 2026 | OUT | $14.80 | Apr 29, 2026 | −20.1% | ✓ right |
| Mar 27, 2026 | IN | $14.15 | Apr 14, 2026 | +4.6% | ✓ right |
| Mar 10, 2026 | OUT | $16.88 | Mar 27, 2026 | −16.2% | ✓ right |
| Feb 5, 2026 | IN | $18.95 | Mar 10, 2026 | −10.9% | ✕ wrong |
| Nov 26, 2025 | OUT | $18.99 | Feb 5, 2026 | −0.2% | ✓ right |
| Nov 20, 2025 | IN | $15.51 | Nov 26, 2025 | +22.4% | ✓ right |
| Sep 15, 2025 | OUT | $7.39 | Nov 20, 2025 | +109.9% | ✕ wrong |
An in call is right when the price rose before the next call; an out call is right when it fell. The latest 12 of 48 calls shown.
How the play works
- In on a close below the lower band (20-day average − 2 standard deviations).
- Out on a close above the 20-day average.
This runs against Bollinger's advice that tags of the bands are not signals. It is shown because so many traders use it.
The case against
Valeriy Zakamulin tested moving-average timing on up to 155 years of U.S. stock data and found no statistically significant edge in the second half of that record. The rules earned their keep in a few severe bear markets and lagged buy and hold for long stretches in between.