How useful is the Advance Decline (A/D) indicator and what can it tell us? The A/D indicator is a breadth indicator and signal used for determining a shift in the directional trend of aggregate markets. It measures the difference between the number of advancing and declining stocks on a daily basis. In doing so, it can provide insight into market sentiment. A rising line signals the cumulative strength of rising stocks in proportion to declining stocks and conversely a falling trend line shows the preponderance of stocks falling in proportion to stocks that are rising. As with every signal there are nuances to understanding the data outputs of the signal itself which in turn can require evaluation in combination with other technical indicators.
As mentioned, when an index is rallying and the A/D line is rising it reflects strong participation among companies in the trend. However, if the index is rising but the A/D line is rising only marginally or remains unchanged, it could indicate that the rally in the index is due to the rise of only a small number of market leaders. Conversely, if indexes are falling but the A/D line is steady or even rising, it can indicate that fewer stocks in aggregate are declining.
On Thursday January 12th 2023, the ratio of advancing to declining stocks on the NYSE closed above 1.97. The last time this happened was in June 2020, when stocks were rallying out of the COVID-induced bear market. This is the 25th time that this has occurred in the last 75 years. In all 24 prior instances the stock market was higher 12 months later. There are no guarrantees of course that the same will happen in this instance. History can signal probabilities but every market cycle and time in history has its own unique attributes.
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