Volume & money flow · daily rule · Consumer & retail
Money Flow Index on Costco
COST with the play, last two years
Shading shows the play's call from the close that triggered it.
Money Flow Index (14)
Dashed lines at 20, 80.
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 COST over exactly the same dates, after costs.
| Play, since 2005 | Hold, since 2005 | Play, 5 yrs | Hold, 5 yrs | |
|---|---|---|---|---|
| Annual return | +11.1% | +16.9% | +7.8% | +17.8% |
| Total return | +888% | +2,875% | +45% | +126% |
| Worst drawdown | −31.4% | −48.0% | −31.4% | −31.4% |
| Volatility | 11.0% | 22.3% | 12.8% | 22.9% |
| Sharpe ratio | 0.85 | 0.73 | 0.36 | 0.67 |
| Time invested | 29% | 100% | ||
| Switches per year | 1.6 | 0 |
Every call, graded
Right on 25 of 35 closed calls (71%). In calls averaged +12.8%; out calls saw COST move +10.2% on average.
| Called | Call | Price | Until | COST moved | Result |
|---|---|---|---|---|---|
| Sep 18, 2026 | IN | $895.31 | now | +6.6% | open |
| Jan 29, 2026 | OUT | $948.70 | Sep 18, 2026 | −5.6% | ✓ right |
| Jul 31, 2025 | IN | $932.90 | Jan 29, 2026 | +1.7% | ✓ right |
| Feb 7, 2025 | OUT | $1,034.97 | Jul 31, 2025 | −9.9% | ✓ right |
| Jan 6, 2025 | IN | $913.89 | Feb 7, 2025 | +13.2% | ✓ right |
| Apr 6, 2023 | OUT | $465.19 | Jan 6, 2025 | +96.5% | ✕ wrong |
| Feb 27, 2023 | IN | $466.19 | Apr 6, 2023 | −0.2% | ✕ wrong |
| Jul 12, 2022 | OUT | $467.12 | Feb 27, 2023 | −0.2% | ✓ right |
| Jan 27, 2022 | IN | $458.01 | Jul 12, 2022 | +2.0% | ✓ right |
| Mar 30, 2021 | OUT | $330.12 | Jan 27, 2022 | +38.7% | ✕ wrong |
| Mar 8, 2021 | IN | $293.94 | Mar 30, 2021 | +12.3% | ✓ right |
| Jun 19, 2019 | OUT | $238.95 | Mar 8, 2021 | +23.0% | ✕ 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 36 calls shown.
How the play works
- In when the 14-day MFI crosses up through 20.
- Out when it crosses down through 80.
The creators also stress divergences, which this rule ignores.
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.