This research aims to apply Gann's theory to forecast the price of stocks being one of the top and most significant technical analysis theories. It is the only theory that links price to time to forecast the market trend and determine the price levels the stock hits in the future, using a set of price and time strategies which were based on precise mathematical, engineering and astronomical principles and foundations. This research starts with a problem of (possibility of forecasting of common stock prices using Gann's theory).The research was conducted on the New York Stock market, which is classified as one of the semi-strong markets, where MSFT was chosen as an intended sample for the period from 2018 to 2022, with weekly and daily closing prices. The research found a number of results, the most prominent of which was the possibility of determining the general trend of the market and determining the price targets that the stock is expected to reach in the future using Gann's theory in markets with semi-strong efficiency.