Indicator Accumulation Swing Index was developed by Welles Wilder, Jr. and is described in his book "New Concepts in Technical Trading Systems". The indicator is a simple index of fluctuations which is similar in its form to price change in financial assets.

Wilder’s book "New Concepts in Technical Trading Systems" provides the following description of the indicator. "When ASI is placed at the same daily chart, the trends figured on the indicator can be compared to the levels on the chart. For those who know how to draw relevant levels of trends, ASI may be helpful tool which indicates the breakthrough of trendline. The wrong breakthrough of trendline on the chart will not be approved with the corresponding lines on the indicator’s chart. Due to the fact that closing price is used to a greater extent, price change during the day is not bad influence on the index of the indicator."

Accumulation Swing Index is also good at trend when it is used simultaneously with SMA(50) indicator as a signal line. The points where ASI crosses SMA upside or downside are trade signals which point out both the entry area in the direction of the trend which is developing and exit area in case the indicator crosses the signal line in the inverse direction.