The Master Time Factor (MTF) is a cycle method developed by W.D. Gann. The MTF is used to forecast the markets by finding the historical cycle that is repeating in the markets at the current time. The most famous use of the MTF was W.D. Gann’s annual forecasts.  W.D. Gann had a forecasting and advisory service from which he would sell an annual market forecast which would cover the next 9 to 12 months. W.D. Gann did not intend the annual forecasts to be a standalone product; they were supplemented by monthly updates and there was the option of a weekly update provided by telegraph service.

"In order to make up an annual forecast, you must refer to my Master 20-year Forecasting Chart and see how these cycles have worked out in the past.  As stated before, the 20-year cycle is the most important cycle for forecasting future market movements.  It is one-third of the 60-year cycle and when three 20-year cycles run out, important bull and bear campaigns terminate. By placing the monthly high and low prices for each of those 20-year periods above each other, it is easy to see how the cycles repeat. No person can study the Master 20-year Forecasting Chart and the cycles without being convinced that the time cycles do repeat at regular intervals and that it is possible to forecast future market movements.  By studying Resistance Levels, Geometric Angles, and Volume of Sales in connection with the cycles, you can determine when the trend is changing at the end of campaigns."  --W. D. Gann