Manager Tenure refers to the amount of time, usually measured in years, a mutual fund manager or management team has been managing a particular mutual fund.
Manager tenure is most important to know when investing in actively-managed mutual funds. Managers of actively-managed funds are actively trying to outperform a particular benchmark, such as the S&P 500; whereas the manager of a passively-managed fund is only investing in the same securities as the benchmark.
When looking at a mutual fund's historic performance, be sure to confirm the manager or management team has been managing the fund for the time frame you are reviewing. For example, if you are attracted to the 5-year return of a mutual fund but the manager tenure is only one year, the 5-year return is not meaningful in making the decision to buy this fund.