貝他係數
beta coefficient (fund investment)
β係數也稱為貝他係數，是一種風險指數，用來衡量個別股票或股票基金相對於整個股市的價格波動情況。根據投資理論，全體市場本身的β係數為1，若基金投資組合淨值的波動大於全體市場的波動幅度，則β係數大於1。反之，若基金投資組合淨值的波動小於全體市場的波動幅度，則β係數就小於1。β係數越大之證券，通常是投機性較強的證券。以美國為例，通常以史坦普五百企業指數(S&P 500)代表股市，貝他係數為1。一個共同基金的貝他係數如果是1.10，表示其波動是股市的1.10 倍，亦即上漲時比市場表現優10%，而下跌時則更差10%;若貝他係數為0．5，則波動情況只及一半。β= 0.5 為低風險股票，β= l. 0 表示為平均風險股票，而β= 2. 0 → 高風險股票，大多數股票的β係數介於0.5到l.5間
β coefficient is also known as a beta, it is a risk index, a measure of individual stocks or stock funds with respect to the price fluctuations of the entire stock market. According to investment theory, the whole market itself β coefficient of 1, if the volatility of investment funds is greater than the combined net worth of all the market volatility, the β coefficient greater than one. Conversely, if the volatility of investment fund is less than the combined net worth of all the market volatility, the β coefficient is less than 1. The larger of the securities β coefficient, usually a strong speculative securities. In the United States, usually the S & P five hundred Enterprises Index (S & P 500) on behalf of the stock market, a beta of 1. A mutual fund if the beta coefficient is 1.10, indicating that stock market volatility is 1.10 times, that is when the market rose more than 10% of excellent performance, while 10 per cent fall even worse; if a beta of 0.5, fluctuations only half. β = 0.5 for the low-risk stocks, β = l. 0 indicates an average risk of the stock, and β = 2. 0 → high-risk stocks, β coefficient of most stocks ranged between 0.5 to l.5