Trading glossary
Momentum
By the PatternX team · Published
Definition
Momentum is the strength and speed of a price move: how far and how fast price has traveled over a recent period. Momentum trading rests on the idea that a strong move can keep going for a while before it fades.
How it's measured
The simplest measures compare the latest price with the price n bars earlier:
- Momentum = latest close − close n bars ago
- Rate of change (ROC) = (latest close − close n bars ago) ÷ close n bars ago × 100
Indicators such as RSI and MACD build on the same idea, with smoothing. Intraday stock traders often use an even simpler gauge, the percentage change from the previous close, which is how gainers and losers lists are ranked.
Why it matters
Momentum describes what has happened, not what will happen. A stock up 12% on heavy volume shows that buyers have been more aggressive than sellers so far; it says nothing certain about the next hour. Strong moves can run further than seems reasonable, and they can also reverse abruptly when early buyers take profits, so exits matter as much as entries.
How momentum is changing is often more useful than its level. A price that keeps rising at a slowing rate is losing strength before it actually turns.
Example
For example, a hypothetical stock closed at $8.00 and trades at $8.80 in premarket, up 10%. Over its last five 1-minute bars it rose from $8.50 to $8.80, a 5-bar ROC of about 3.5%. Ten minutes later it is at $8.85, but five bars earlier it was already at $8.80, so the 5-bar ROC has fallen to about 0.6%. Still up, but stalling.
Common mistakes
- Chasing: buying after the move is extended, where the distance to a sensible stop is largest.
- Confusing momentum with trend: a short burst can run against a longer downtrend drawn with a trendline.
- Ignoring participation: a move on low relative volume has fewer traders behind it, and many fast movers trade thinly before the open.
How PatternX uses it
Momentum Lab (Elite) runs three rule-based strategies on US stocks: Premarket Momentum Breakout, Momentum Reversal and Opening Momentum Continuation. It watches lists of the biggest gainers and losers from your data source, 50 of each, refreshed every 15 seconds. The strategies only detect; filters such as minimum price, volume, spread and a mandatory market-cap floor decide whether a candidate may trade. The breakout strategy also refuses to chase: by default it skips a stock already seen more than 8% from its reference.
In PatternX AI (Pro and Elite), one of the eight factors in the context layer is momentum, measured as RSI(14) in the trade's direction. For strategy design, see momentum trading strategy.