Mean reversion · daily rule · Semiconductors
Bollinger Reversion on Teradyne
What the play says
TER with the play, last two years
Shading shows the play's call from the close that triggered it.
Growth of $10,000 since 2005
Log scale. After trading costs, with T-bill interest while out.
The record
The play against buying and holding TER over exactly the same dates, after costs.
| Play, since 2005 | Hold, since 2005 | Play, 5 yrs | Hold, 5 yrs | |
|---|---|---|---|---|
| Annual return | −0.9% | +16.0% | −1.2% | +29.2% |
| Total return | −17% | +2,396% | −6% | +257% |
| Worst drawdown | −66.0% | −83.8% | −40.8% | −59.1% |
| Volatility | 24.6% | 44.2% | 26.6% | 54.1% |
| Sharpe ratio | 0.02 | 0.52 | −0.05 | 0.67 |
| Time invested | 25% | 100% | ||
| Switches per year | 8.2 | 0 |
Every call, graded
Right on 100 of 178 closed calls (56%). In calls averaged +0.0%; out calls saw TER move +6.6% on average.
| Called | Call | Price | Until | TER moved | Result |
|---|---|---|---|---|---|
| Mar 24, 2026 | OUT | $319.90 | now | +18.9% | open |
| Mar 6, 2026 | IN | $272.84 | Mar 24, 2026 | +17.2% | ✓ right |
| Apr 24, 2025 | OUT | $76.96 | Mar 6, 2026 | +254.5% | ✕ wrong |
| Feb 27, 2025 | IN | $108.33 | Apr 24, 2025 | −29.0% | ✕ wrong |
| Feb 20, 2025 | OUT | $118.02 | Feb 27, 2025 | −8.2% | ✓ right |
| Jan 27, 2025 | IN | $119.61 | Feb 20, 2025 | −1.3% | ✕ wrong |
| Nov 22, 2024 | OUT | $107.49 | Jan 27, 2025 | +11.3% | ✕ wrong |
| Oct 24, 2024 | IN | $109.99 | Nov 22, 2024 | −2.3% | ✕ wrong |
| Aug 15, 2024 | OUT | $130.74 | Oct 24, 2024 | −15.9% | ✓ right |
| Jul 25, 2024 | IN | $123.40 | Aug 15, 2024 | +5.9% | ✓ right |
| Apr 25, 2024 | OUT | $107.99 | Jul 25, 2024 | +14.3% | ✕ wrong |
| Apr 17, 2024 | IN | $101.21 | Apr 25, 2024 | +6.7% | ✓ 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 179 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.