Mean reversion · daily rule · Industrials & materials
Bollinger Reversion on Mullen Group
What the play says
MTL with the play, last two years
Shading shows the play's call from the close that triggered it.
Growth of C$10,000 since 2005
Log scale. After trading costs, with T-bill interest while out.
The record
The play against buying and holding MTL over exactly the same dates, after costs.
| Play, since 2005 | Hold, since 2005 | Play, 5 yrs | Hold, 5 yrs | |
|---|---|---|---|---|
| Annual return | +2.8% | +7.9% | +9.6% | +21.6% |
| Total return | +82% | +415% | +58% | +164% |
| Worst drawdown | −56.1% | −83.4% | −14.1% | −21.6% |
| Volatility | 18.2% | 32.6% | 12.0% | 27.0% |
| Sharpe ratio | 0.15 | 0.34 | 0.51 | 0.72 |
| Time invested | 23% | 100% | ||
| Switches per year | 8.9 | 0 |
Every call, graded
Right on 127 of 192 closed calls (66%). In calls averaged +0.7%; out calls saw MTL move +2.4% on average.
| Called | Call | Price | Until | MTL moved | Result |
|---|---|---|---|---|---|
| Sep 4, 2026 | OUT | C$25.72 | now | +9.8% | open |
| Aug 25, 2026 | IN | C$25.03 | Sep 4, 2026 | +2.8% | ✓ right |
| Mar 24, 2026 | OUT | C$16.41 | Aug 25, 2026 | +52.5% | ✕ wrong |
| Mar 12, 2026 | IN | C$15.85 | Mar 24, 2026 | +3.6% | ✓ right |
| Aug 12, 2025 | OUT | C$13.01 | Mar 12, 2026 | +21.8% | ✕ wrong |
| Jul 24, 2025 | IN | C$12.51 | Aug 12, 2025 | +4.0% | ✓ right |
| Apr 9, 2025 | OUT | C$11.75 | Jul 24, 2025 | +6.4% | ✕ wrong |
| Mar 28, 2025 | IN | C$11.70 | Apr 9, 2025 | +0.5% | ✓ right |
| Mar 26, 2025 | OUT | C$12.05 | Mar 28, 2025 | −2.9% | ✓ right |
| Feb 3, 2025 | IN | C$13.09 | Mar 26, 2025 | −8.0% | ✕ wrong |
| Jan 6, 2025 | OUT | C$13.74 | Feb 3, 2025 | −4.7% | ✓ right |
| Dec 18, 2024 | IN | C$13.48 | Jan 6, 2025 | +1.9% | ✓ right |
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 193 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.