Making reliable forecasts is very important for financial analysis. For this reason, financial analysts make analyzes using different models. Financial analysts try to make the most accurate estimation in these analyzes. The Artificial Neural Network model is a widely used method in the field of finance. In this study, BIST 100 index was estimated using Artificial Neural Networks and Regression model. By using the closing prices of the BIST 100 index between 2010 and 2020, the closing values of the BIST 100 index for 2021 were estimated. Moreover, the Regression model and Artificial Neural Network model predictions were obtained. The mean square error of the neural networks and Regression model was also found. Finally, according to the result of the mean of error squares, the performance of the models was compared and seen that the Artificial Neural Network model was better.