Mean reversion · daily rule · Indexes & ETFs
Bollinger Reversion on Silver ETF
What the play says
SLV with the play, last two years
Shading shows the play's call from the close that triggered it.
Growth of $10,000 since 2006
Log scale. After trading costs, with T-bill interest while out.
The record
The play against buying and holding SLV over exactly the same dates, after costs.
| Play, since 2006 | Hold, since 2006 | Play, 5 yrs | Hold, 5 yrs | |
|---|---|---|---|---|
| Annual return | +0.4% | +7.3% | +6.1% | +20.3% |
| Total return | +8% | +322% | +34% | +151% |
| Worst drawdown | −58.5% | −76.3% | −20.6% | −52.3% |
| Volatility | 17.2% | 33.3% | 14.5% | 37.4% |
| Sharpe ratio | 0.01 | 0.33 | 0.22 | 0.59 |
| Time invested | 26% | 100% | ||
| Switches per year | 8.3 | 0 |
Every call, graded
Right on 100 of 169 closed calls (59%). In calls averaged +0.1%; out calls saw SLV move +3.0% on average.
| Called | Call | Price | Until | SLV moved | Result |
|---|---|---|---|---|---|
| Sep 28, 2026 | IN | $54.95 | now | −2.7% | open |
| Jul 22, 2026 | OUT | $53.92 | Sep 28, 2026 | +1.9% | ✕ wrong |
| Jun 10, 2026 | IN | $57.66 | Jul 22, 2026 | −6.5% | ✕ wrong |
| Apr 8, 2026 | OUT | $67.47 | Jun 10, 2026 | −14.5% | ✓ right |
| Mar 18, 2026 | IN | $68.70 | Apr 8, 2026 | −1.8% | ✕ wrong |
| Apr 16, 2025 | OUT | $29.76 | Mar 18, 2026 | +130.8% | ✕ wrong |
| Apr 3, 2025 | IN | $28.89 | Apr 16, 2025 | +3.0% | ✓ right |
| Jan 8, 2025 | OUT | $27.40 | Apr 3, 2025 | +5.4% | ✕ wrong |
| Dec 18, 2024 | IN | $26.85 | Jan 8, 2025 | +2.0% | ✓ right |
| Aug 15, 2024 | OUT | $25.86 | Dec 18, 2024 | +3.8% | ✕ wrong |
| Jul 25, 2024 | IN | $25.41 | Aug 15, 2024 | +1.8% | ✓ right |
| May 9, 2024 | OUT | $25.86 | Jul 25, 2024 | −1.7% | ✓ 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 170 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.