The most obvious disadvantage of active management is that the fund manager may make bad investment choices or follow an unsound theory in managing the portfolio. Unless active management is performed by a robo-advisor the fees associated with active management are generally also higher than those associated with passive management, even if frequent trading is not present, reflecting in part the additional research costs associated with active investing. Those who are considering investing in an actively managed mutual fund should evaluate the fund's prospectus carefully. Data from recent decades demonstrates that the majority of actively managed large and mid-cap stock funds in United States fail to outperform their passive stock index counterparts.