Momentum is showing the difference between current closing price and the close N periods ago. This indicator measures the acceleration of the price move and could be calculated by the following formula:
Momentum = C(t) - C(t-n), where
C(t) is the latest closing price
C(t-n) is the closing price ānā ago
The idea is that if the price is higher than ānā periods ago it will continue to move up and vice versa. Momentum indicator is generating the following signals: