Volume & money flow · daily rule · Healthcare
Money Flow Index on DexCom
DXCM 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 DXCM over exactly the same dates, after costs.
| Play, since 2005 | Hold, since 2005 | Play, 5 yrs | Hold, 5 yrs | |
|---|---|---|---|---|
| Annual return | +2.3% | +17.9% | +0.9% | −9.1% |
| Total return | +64% | +3,302% | +4% | −38% |
| Worst drawdown | −90.4% | −94.6% | −46.7% | −66.3% |
| Volatility | 40.2% | 54.3% | 39.4% | 47.3% |
| Sharpe ratio | 0.22 | 0.54 | 0.14 | −0.03 |
| Time invested | 40% | 100% | ||
| Switches per year | 2.1 | 0 |
Every call, graded
Right on 24 of 46 closed calls (52%). In calls averaged +4.1%; out calls saw DXCM move +25.4% on average.
| Called | Call | Price | Until | DXCM moved | Result |
|---|---|---|---|---|---|
| Jun 2, 2026 | OUT | $73.45 | now | +15.8% | open |
| Mar 17, 2026 | IN | $67.32 | Jun 2, 2026 | +9.1% | ✓ right |
| Oct 28, 2025 | OUT | $69.23 | Mar 17, 2026 | −2.8% | ✓ right |
| Jun 24, 2025 | IN | $87.57 | Oct 28, 2025 | −20.9% | ✕ wrong |
| May 13, 2025 | OUT | $84.11 | Jun 24, 2025 | +4.1% | ✕ wrong |
| Mar 19, 2025 | IN | $73.38 | May 13, 2025 | +14.6% | ✓ right |
| Jan 28, 2025 | OUT | $88.35 | Mar 19, 2025 | −16.9% | ✓ right |
| Jul 11, 2024 | IN | $112.66 | Jan 28, 2025 | −21.6% | ✕ wrong |
| Nov 28, 2023 | OUT | $112.20 | Jul 11, 2024 | +0.4% | ✕ wrong |
| Aug 7, 2023 | IN | $120.97 | Nov 28, 2023 | −7.2% | ✕ wrong |
| Jun 21, 2023 | OUT | $127.86 | Aug 7, 2023 | −5.4% | ✓ right |
| Sep 6, 2022 | IN | $82.03 | Jun 21, 2023 | +55.9% | ✓ 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 47 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.