fund managers have an incentive to manipulate their betas mutual fund return data is often outdated mutual fund portfolios have a large amount of unsystematic risk portfolio alphas (a's) vary from fund to fund O portfolio turnover can be high The empirical betas of actively managed mutual funds may be suspect because: fund managers have an incentive to manipulate their betas mutual fund return data is often outdated O mutual fund portfolios have a large amount of unsystematic risk O portfolio alphas (as) vary from fund to fund O portfolio turnover can be high