Rate of Change
Measures the percentage change in price over a specified number of periods, oscillating above and below zero to show momentum direction and speed.
Description
Rate of Change (ROC) is one of the simplest momentum indicators. It directly measures how much price has changed over a given number of periods, expressed as a percentage. Positive values mean price is higher than it was N periods ago; negative values mean it is lower. The zero line is the key reference.
How It Works
ROC = (current close − close N periods ago) / close N periods ago × 100. Default period: 12. A 12-period daily ROC tells you how much price has changed over the past 12 trading days, as a percentage. There are no smoothing calculations — the result is raw and responsive.
How to Read It
Above zero: price is higher than N periods ago — bullish momentum. Below zero: price is lower — bearish momentum. Rising ROC while above zero indicates accelerating upside momentum; falling ROC while still above zero indicates decelerating momentum that may be near a peak. Zero-line crossovers signal a momentum shift. Divergence between ROC and price often warns of reversals.
Common Uses
- Confirming momentum alongside trend indicators
- Zero-line crossovers as trend-change signals
- Divergence analysis at price extremes
- Identifying momentum acceleration and deceleration
Caveats
ROC is sensitive to “old data drop-off” — when a sharp move from N periods ago falls out of the calculation window, ROC can change dramatically even if current price is unchanged. This creates false signals. The indicator is also highly sensitive to the choice of period; short periods produce noise, long periods produce lag. ROC is most useful as a confirmation tool rather than a standalone signal generator.