The One-Day Reversal (also known as a "Key Reversal Day") is one of the most powerful single signals in technical analysis. It occurs when price breaks out in the direction of the trend on a single trading day — and then completely reverses. The signal shows: the prior move was exhausted.
Recognition Rules
| Criterion | Bullish ODR | Bearish ODR |
|---|---|---|
| New extreme | New multi-week intraday low | New multi-week intraday high |
| Close | Close well above the opening and prior day's close | Close well below the opening and prior day's close |
| Volume | Noticeably higher than the past 10 days | Noticeably higher than the past 10 days |
| Confirmation | Next day also closes higher | Next day also closes lower |
Distinction from Doji / Hammer
A hammer is a single candle pattern — it only requires a specific candle shape. With a One-Day Reversal, magnitude and volume also count. An intraday low with extreme volume and a strong close in the opposite direction is significantly more reliable than a simple hammer without a volume spike.
Historical example: October 9, 2002 was a classic bullish One-Day Reversal on the S&P 500 — almost exactly the low of the dot-com crash. Similar days marked the lows in March 2009 (financial crisis) and March 2020 (COVID crash). Such days are often only recognized in hindsight — but the volume and candle structure are characteristic.