Momentum · month-end rule · Media & telecom
12-1 Momentum on T-Mobile US
What the play says
Latest reading: 12-1 return −23.0%
TMUS with the play, last two years
Shading shows the play's call from the close that triggered it.
Return from 12 months to 1 month ago
Dashed line at 0.
Growth of $10,000 since 2008
Log scale. After trading costs, with T-bill interest while out.
The record
The play against buying and holding TMUS over exactly the same dates, after costs.
| Play, since 2008 | Hold, since 2008 | Play, 5 yrs | Hold, 5 yrs | |
|---|---|---|---|---|
| Annual return | +8.6% | +9.0% | +5.4% | +6.8% |
| Total return | +353% | +390% | +30% | +39% |
| Worst drawdown | −65.2% | −74.7% | −25.8% | −44.0% |
| Volatility | 25.9% | 38.1% | 18.0% | 26.1% |
| Sharpe ratio | 0.40 | 0.38 | 0.17 | 0.24 |
| Time invested | 66% | 100% | ||
| Switches per year | 1.2 | 0 |
Every call, graded
Right on 10 of 22 closed calls (45%). In calls averaged +16.9%; out calls saw TMUS move +7.7% on average.
| Called | Call | Price | Until | TMUS moved | Result |
|---|---|---|---|---|---|
| Nov 28, 2025 | OUT | $205.70 | now | −25.3% | open |
| Dec 29, 2023 | IN | $153.11 | Nov 28, 2025 | +34.3% | ✓ right |
| Oct 31, 2023 | OUT | $136.78 | Dec 29, 2023 | +11.9% | ✕ wrong |
| Sep 29, 2023 | IN | $133.16 | Oct 31, 2023 | +2.7% | ✓ right |
| Jul 31, 2023 | OUT | $130.99 | Sep 29, 2023 | +1.7% | ✕ wrong |
| Aug 31, 2022 | IN | $136.88 | Jul 31, 2023 | −4.3% | ✕ wrong |
| Nov 30, 2021 | OUT | $103.46 | Aug 31, 2022 | +32.3% | ✕ wrong |
| Feb 28, 2019 | IN | $68.66 | Nov 30, 2021 | +50.7% | ✓ right |
| Jan 31, 2019 | OUT | $66.20 | Feb 28, 2019 | +3.7% | ✕ wrong |
| Sep 28, 2018 | IN | $66.73 | Jan 31, 2019 | −0.8% | ✕ wrong |
| Mar 29, 2018 | OUT | $58.04 | Sep 28, 2018 | +15.0% | ✕ wrong |
| Jun 30, 2015 | IN | $36.86 | Mar 29, 2018 | +57.4% | ✓ 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 23 calls shown.
How the play works
- In at month-end when the return from 12 months ago to 1 month ago is above zero.
- Out when it is zero or below.
Jegadeesh and Titman ranked thousands of stocks and bought the winners. Testing one stock against zero is time-series momentum, a related idea.
The skip-a-month form came later; their 1993 paper skipped at most a week.
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.