In technical analysis, an index of the number of stocks reaching a new high minus the number of stocks reaching a new low. This is used to determine whether a market movement is sustainable. A positive high-low index when the market has gone up means that that market is likely to continue to rise. However, mixed signals (i.e. a negative high-low index when the market has risen or vice versa) indicates that the current market movement is unlikely to continue.
A cumulative tabulation of the number of stocks reaching new highs minus the number of stocks reaching new lows. Technical analysts use the high-low index to measure the strength of the market's movement. In general, movement of the high-low index in the same direction as the market confirms the market's movement and indicates that this movement is likely to continue in the same direction.