The capital asset pricing model (CAPM) is a model used to determine a theoretically appropriate rate of return of an asset, to make decision about adding assets to a well-diversified portfolio. The past behavior of the price of a security and the share price index plays an important role in security analysis. So, analysis of the stability of beta in Indian stock market is relevant in explaining the first parity between risk and return. the study aims at identify the systematic risk and average rate of return on equity an Indian stock market for the period of 10 years for the stock indices of Nifty 50 and next 50 Nifty. The results show that, among the 100 companies the beta stability stock market performance or variation of beta is totally different. Here there is no negative value of variation across all beta variability and all positive variability of beta.