A cycle convergence occurs when two or more of these numbers are found on the same trading day or week, at some point in future and with it... increases the chances of marking a top or bottom, in these time frames. An exception, when used isolated (no convergence) the 90 and 180 numbers are powerful enough to cause market reversals. This is also my own experience. A leeway of +/- 1 day (short term) or week (mid term) is usually given for the trading day or week, which marks such a cycle convergence in the stock market.
But these future points in time, don't necessarily say anything about whether it will mark a top or bottom. So one technique used to get a clue, is to observe the directional trend going into these GA time frames (the so called Gann Angle day or week, given the leeway as mentioned above). An example, when market prices have entered a GA time window and the trend going into it is bullish, (positive) often a bearish (negative) market reversal will be the outcome and vice versa.
Below is a recent daily and weekly chart, which shows past short & mid term forecasts, based on this cycle technique. To get future GA's, simply sign up to the Free Trader's Tips Newsletter below, which also include other advanced analysis techniques. Here is a recent example issue for a peek into what you can get with a no cost subscription.
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