Trend following · weekly rule · Indexes & ETFs
Zweig 4% Model on S&P 500 ETF
What the play says
SPY 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 SPY over exactly the same dates, after costs.
| Play, since 2005 | Hold, since 2005 | Play, 5 yrs | Hold, 5 yrs | |
|---|---|---|---|---|
| Annual return | +6.3% | +11.0% | +11.0% | +13.9% |
| Total return | +278% | +861% | +68% | +91% |
| Worst drawdown | −39.0% | −55.2% | −20.3% | −24.5% |
| Volatility | 13.1% | 18.9% | 12.3% | 17.1% |
| Sharpe ratio | 0.40 | 0.55 | 0.60 | 0.62 |
| Time invested | 78% | 100% | ||
| Switches per year | 5.4 | 0 |
Every call, graded
Right on 43 of 118 closed calls (36%). In calls averaged +2.4%; out calls saw SPY move +1.8% on average.
| Called | Call | Price | Until | SPY moved | Result |
|---|---|---|---|---|---|
| Apr 10, 2026 | IN | $676.03 | now | +15.1% | open |
| Mar 13, 2026 | OUT | $657.16 | Apr 10, 2026 | +2.9% | ✕ wrong |
| Apr 11, 2025 | IN | $525.23 | Mar 13, 2026 | +25.1% | ✓ right |
| Mar 7, 2025 | OUT | $564.82 | Apr 11, 2025 | −7.0% | ✓ right |
| Jan 24, 2025 | IN | $596.26 | Mar 7, 2025 | −5.3% | ✕ wrong |
| Jan 10, 2025 | OUT | $569.31 | Jan 24, 2025 | +4.7% | ✕ wrong |
| Sep 13, 2024 | IN | $547.65 | Jan 10, 2025 | +4.0% | ✓ right |
| Sep 6, 2024 | OUT | $526.56 | Sep 13, 2024 | +4.0% | ✕ wrong |
| Aug 16, 2024 | IN | $540.15 | Sep 6, 2024 | −2.5% | ✕ wrong |
| Aug 2, 2024 | OUT | $519.29 | Aug 16, 2024 | +4.0% | ✕ wrong |
| May 10, 2024 | IN | $505.90 | Aug 2, 2024 | +2.6% | ✓ right |
| Apr 19, 2024 | OUT | $480.96 | May 10, 2024 | +5.2% | ✕ 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 119 calls shown.
How the play works
- In when a weekly close is 4% above the lowest weekly close since the last sell.
- Out when a weekly close is 4% below the highest weekly close since the last buy.
Zweig applied it to the Value Line index, not single stocks. A 4% band on a volatile stock will switch far more often.
Some sources credit Ned Davis with first developing 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.