A passive mutual fund invests in a portfolio that mirrors the component of a market index. For example, an S&P 500 index fund is invested in the 500 stocks of Standard & Poor’s 500 Index. There is no attempt made to try to determine which stocks are expected to do well and which are not.
Actively managed funds are managed by an individual manager, co-managers, or a team of managers. The mangers try to buy stocks that they think will outperform the market.
The costs associated with passive investing are lower than the costs of active management. Active managers attempt to justify their higher costs by doing better in either up or down markets.