If the AD volume creates a higher ratio than the AD ratio, TRIN will be below one.
If the AD volume has a lower ratio than the AD ratio, TRIN will be higher than one.
TRIN readings below one usually accompany strong price increases, as strong volume in rising stocks fuels a rally.
A TRIN value above one usually accompanies a strong price decline, as strong volume on falling assets encourages a sell-off.
The Arms Index moves opposite to the price trajectory of the Index. As discussed above, a strong price rally will cause TRIN to move to lower levels. A fall in the index will lead to an increase in TRIN.