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What happens after the Hang Seng rises 20% in three months?
It has happened 27 times since 1987. A year after it began, the S&P 500 was up 20 of 27 times, with a median move of +8.9%. On an ordinary day in the same years the median was +10.9%, up 78% of the time.
Hang Seng up more than 20% over 3 months. Not true on 2026-09-25.
What came next
| 1 month later | 1 year later | 3 years later | |
|---|---|---|---|
| S&P 500 | +0.0% 56% up · n 27 · normal +1.2% | +8.9% 74% up · n 27 · normal +10.9% | +26.8% 81% up · n 27 · normal +32.5% |
| Gold | +0.3% 52% up · n 27 · normal +0.0% | +0.2% 56% up · n 27 · normal +2.2% | +5.7% 59% up · n 27 · normal +11.7% |
| Oil | +5.9% 78% up · n 27 · normal +1.0% | +19.4% 59% up · n 27 · normal +5.2% | +8.3% 63% up · n 27 · normal +13.0% |
| 10-year yield (pts) | +0.12 pts 70% up · n 27 · normal -0.02 pts | -0.02 pts 44% up · n 27 · normal -0.22 pts | -0.37 pts 33% up · n 27 · normal -0.50 pts |
| Inflation, CPI y/y (pts) | +0.04 pts 52% up · n 27 · normal -0.00 pts | +0.23 pts 63% up · n 27 · normal +0.05 pts | -0.33 pts 44% up · n 27 · normal -0.27 pts |
| Unemployment rate (pts) | +0.05 pts 50% up · n 24 · normal 0.00 pts | -0.30 pts 30% up · n 27 · normal -0.30 pts | -0.70 pts 33% up · n 27 · normal -0.80 pts |
Median move after each episode began, how often it rose, and how many episodes had data. "Normal" is the same move from any trading day in the same years.
Every time it happened
- 2021-01-19 · true for 4 trading days · S&P 500 a year later: +19.3%
- 2012-02-22 · true for 3 trading days · S&P 500 a year later: +10.7%
- 2009-04-23 · true for 74 trading days · S&P 500 a year later: +42.9%
- 2007-09-24 · true for 48 trading days · S&P 500 a year later: -21.7%
- 2003-10-03 · true for 11 trading days · S&P 500 a year later: +9.9%
- 2003-07-28 · true for 1 trading day · S&P 500 a year later: +9.9%
- 2001-12-12 · true for 8 trading days · S&P 500 a year later: -20.7%
- 2000-08-17 · true for 9 trading days · S&P 500 a year later: -22.3%
- 2000-07-17 · true for 1 trading day · S&P 500 a year later: -19.6%
- 1999-12-03 · true for 27 trading days · S&P 500 a year later: -8.2%
- 1999-04-16 · true for 56 trading days · S&P 500 a year later: +2.8%
- 1998-10-26 · true for 52 trading days · S&P 500 a year later: +19.5%
- 1998-04-09 · true for 8 trading days · S&P 500 a year later: +21.4%
- 1997-06-20 · true for 29 trading days · S&P 500 a year later: +22.5%
- 1996-11-29 · true for 5 trading days · S&P 500 a year later: +26.2%
- 1996-02-09 · true for 7 trading days · S&P 500 a year later: +20.3%
- 1995-04-24 · true for 2 trading days · S&P 500 a year later: +27.0%
- 1993-10-14 · true for 81 trading days · S&P 500 a year later: +0.5%
- 1993-05-04 · true for 6 trading days · S&P 500 a year later: +1.7%
- 1993-03-04 · true for 6 trading days · S&P 500 a year later: +3.9%
- 1992-05-04 · true for 36 trading days · S&P 500 a year later: +6.5%
- 1992-03-02 · true for 12 trading days · S&P 500 a year later: +8.6%
- 1991-03-18 · true for 20 trading days · S&P 500 a year later: +10.1%
- 1989-09-22 · true for 8 trading days · S&P 500 a year later: -10.3%
- 1989-02-03 · true for 12 trading days · S&P 500 a year later: +11.4%
- 1988-03-04 · true for 9 trading days · S&P 500 a year later: +8.9%
- 1987-06-16 · true for 48 trading days · S&P 500 a year later: -9.9%
- 27 separate episodes: a new one starts after 30 days without a match, so one long selloff counts once.
- Try enough situations and one will look like an edge by chance.
- Macro numbers are as published at the time. Stocks include companies that later died.
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