The market timing ability of mutual fund managers can be defined as the ability to anticipate whether the general stock market is going to rise or fall and to adjust the composition of their portfolios accordingly . that is , if the managers think they have the ability to anticipate that the market is going to rise , they shift the composition of their portfolios they manage from less to more volatile securities . if they think the market is going to fall , they shift into the opposite direction 證券投資基金(以下簡稱“基金” )的擇時能力是指基金經(jīng)理的市場時機(jī)把握能力,即如果基金經(jīng)理相信自己能夠準(zhǔn)確預(yù)測市場趨勢,他將根據(jù)期望的市場走勢調(diào)整其投資組合的風(fēng)險水平,在預(yù)測市場收益上升時增加組合的風(fēng)險水平,下降時降低組合的風(fēng)險水平,通過高風(fēng)險資產(chǎn)和低風(fēng)險(或無風(fēng)險)資產(chǎn)之間的不斷轉(zhuǎn)換來獲取超額收益。