Mean reversion · daily rule · Consumer & retail
Bollinger Reversion on Dollarama
What the play says
DOL with the play, last two years
Shading shows the play's call from the close that triggered it.
Growth of C$10,000 since 2009
Log scale. After trading costs, with T-bill interest while out.
The record
The play against buying and holding DOL over exactly the same dates, after costs.
| Play, since 2009 | Hold, since 2009 | Play, 5 yrs | Hold, 5 yrs | |
|---|---|---|---|---|
| Annual return | +9.0% | +28.1% | +12.5% | +28.6% |
| Total return | +330% | +6,426% | +80% | +250% |
| Worst drawdown | −16.8% | −45.1% | −12.2% | −19.6% |
| Volatility | 11.4% | 23.0% | 11.6% | 22.2% |
| Sharpe ratio | 0.69 | 1.13 | 0.75 | 1.08 |
| Time invested | 17% | 100% | ||
| Switches per year | 8.2 | 0 |
Every call, graded
Right on 84 of 138 closed calls (61%). In calls averaged +2.0%; out calls saw DOL move +4.7% on average.
| Called | Call | Price | Until | DOL moved | Result |
|---|---|---|---|---|---|
| Sep 21, 2026 | OUT | C$178.59 | now | +8.0% | open |
| Aug 25, 2026 | IN | C$183.33 | Sep 21, 2026 | −2.6% | ✕ wrong |
| Jul 27, 2026 | OUT | C$187.61 | Aug 25, 2026 | −2.3% | ✓ right |
| Jul 23, 2026 | IN | C$181.38 | Jul 27, 2026 | +3.4% | ✓ right |
| Apr 14, 2026 | OUT | C$176.25 | Jul 23, 2026 | +2.9% | ✕ wrong |
| Mar 18, 2026 | IN | C$189.22 | Apr 14, 2026 | −6.9% | ✕ wrong |
| Feb 4, 2026 | OUT | C$194.92 | Mar 18, 2026 | −2.9% | ✓ right |
| Jan 21, 2026 | IN | C$192.63 | Feb 4, 2026 | +1.2% | ✓ right |
| Oct 17, 2025 | OUT | C$182.51 | Jan 21, 2026 | +5.5% | ✕ wrong |
| Oct 1, 2025 | IN | C$181.22 | Oct 17, 2025 | +0.7% | ✓ right |
| Sep 19, 2025 | OUT | C$189.07 | Oct 1, 2025 | −4.1% | ✓ right |
| Aug 27, 2025 | IN | C$184.49 | Sep 19, 2025 | +2.5% | ✓ 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 139 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.