finance question..

The CAPM is usually expressed:


圖片參考：http://upload.wikimedia.org/math/d/4/6/d4655d2b70a5fd53835190856e2e9641.png


β, Beta, is the measure of asset sensitivity to a movement in the overall market

圖片參考：http://upload.wikimedia.org/math/a/9/8/a98dd1aa846c5d3981fdee7390b7fa3d.png
is the market premium, the historically observed excess return of the market over the risk-free rate.
所以β是一個用來量度某一特定股票對market portfolio's的敏感度
現在
market risk is the same as the market portfolio's
因為market portfolio's 的β值是1﹐所以這隻股票的beta值亦應是1
只有risk free asset 的 beta 值才會是0
你由條公式都可以睇到

很好, 你令我對finance認識多了.