How to conduct this event study? This event study is trying to know what is the impact of changing the monetary policy in Egypt and how this affect the Egyptian stock market. The strategy in our research is to concentrate on 125 days for our event study and the data for the stocks w will select it will be 15days before the event and 10 days after the event. The first -120 days will be estimated window and from -5 to +10 will be the event window. We will use Market model in this study to discover if there is any up normal returns. We will analyse the selected data as follow. Rit = ln (pt/pt-1) Rit = the return of the security each day Pt = the closing price each day Pt-1 = the closing price and time minus 1 Rmt = ln (lt /lt-1) Rmt = the average return during the day Lt = the closing price of the market Lt -1 = the price of the last day index Ri =αi + βiRmt + Ɛi Ri = the return of the security in the day Rm = the return of the market Ɛ = the error that affected the security αI and βI = show the liner relationship between the securities and the market return we will measure the up normal return. We can get the up normal return by knowing the deference between the actual return and the normal return that’s why we will use CAPM model ARit=Rit-αi-βiRmt The main reason of this research is to find if this event has an impact on the stock market and if this announcement increased the volume of the stock market. This event study will measure how the Egyptian stock market will react after the announcing of changing the monetary policy and change it to floating change rate. The hypothesis fore this research will be: H0: changing the monetary policy in Egypt has effected the performance of the Egyptian stock market. H1: changing the monetary policy in Egypt does not effected the performance of the Egyptian stock market. In this research, we will collect data from the Egyptian stock market, yahoo finance and Bloomberg. Regression model is important to use in this event study and we will use software like SPSS or gretl to do T test for the three large sectors in the stock market. Each sector we will choose 10 companies from each of them. Trying to measure the up normal return on each sector after the announcement of changing the monetary policy. According to Polinsky and Shavell (2007) The event study has main points. The first thing is to define the event. Second measuring the returns on the stocks that we will choose, third calculating the up normal return and knowing if it significant or not.