**BUK**RG** The beta of a stock or portfolio relates to a numeral notation depicting the link between its returns and that of the entire financial market. The beta of a fund is specified mathematically as the ratio of the covariance of returns implied portfolio with the market and the variance of profitability implied market, either: \ beta \ = \ frac (Cov (r_p, R_M )) (Var (R_M)). It is a useful indicator in relation to the development of a strategy for risk aversion. Beta also pertains to the relationship between the profitability of assets and market volatility in respect of price changes which are essential for profitability. For example, if the beta of a share is 0.8, its price has ranged on average in the previous period to 0.8% when the market varied from 1%. That is the sensitivity or elasticity of stock price over the market index representing the market. The beta coefficient constitutes a key parameter in the capital asset pricing model (CAPM). It serves the purpose of measuring the aspect of asset statistical variance not mitigated by the portfolio risk aversion attempts, due to correlation with the return of the other assets. Beta can be approximated for single commercial enterprise by applying regression analysis against the stock market index. It is also an indicator of risk and there is a link between profitability and risk, the more the price is expected to rise sharply when the market is bullish, the greater the risk to fall sharply when it is bearish. Beta is also known as financial elasticity or correlated relative volatility, and referenced as a measure of the reactivity of the asset's returns to factors such as market returns, systematic risk, or market risk. The process of beta measurement informs on the level of market volatility and liquidity. Model APT (arbitrage pricing theory) is a generalization of the assessment model that uses financial assets, not just one beta, but a series of several beta coefficients each corresponding to one factor of change and yield. The beta factor is included in the Capital Asset Pricing Model (CAPM) financial-building theories, the key figure for acquiring an investment or financing measure as regards systematic risk (also called market risk). The beta factor can be illustrated in three modes, and the first one pertains to the investment going into volatility than the overall, the second touches on the investment being parallel to the overall market moves, and the third implies that the stock is moving at a slower rate than the overall market.