As technical analysis depends on indicators to predict the movement of a stock , why a particular indicator fails. a) after  some time of use in the market b) for particular stocks ?

Let me clear two assumptions for you now1. All indicators either follow the price or lead-based on momentum but are dependent on the underlying stock. A stock with a clear trend and behaviour will also have signs which will give clear direction.2. Every symbol has an active working percentage which is not stagnant. Like RSI can provide you 70-80% accuracy on a trending market, but if the market is sideways it's skill might go below 40% So after you've understood the above, it's pretty simple. For your question a) it may be because the market dynamics have changed and hence the indicator is less useful for the current scenario.b) the index will always be based on the underlying stock, so if the stock is manipulated or has unclear/choppy trend, the indicator will also give ambiguous results. read less

It is no indicator that fails in the market; what goes wrong is our view. Technical Analysis is based on certain assumptions as well as probabilities, not certainties.One should understand the logic (maths) behind the formation of a particular indicator. Some would be leading, and some are lagging. Based on your view and time horizon, you have to use the Indicator. read less