A measure of how frequently assets within a fund are bought and sold by the managers. Portfolio turnover is calculated by taking either the total amount of new securities purchased or the amount of securities sold - whichever is less - over a particular period, divided by the total net asset value (NAV) of the fund. The measurement is usually reported for a 12-month time period.
The portfolio turnover measurement should be considered by an investor before deciding to purchase a given mutual fund or similar financial instrument. After all, a firm with a high turnover rate will incur more transaction costs than a fund with a lower rate. Unless the superior asset selection renders benefits that offset the added transaction costs they cause, a less active trading posture may generate higher fund returns.
In addition, cost conscious fund investors should take note that the transactional brokerage fee costs are not included in the calculation of a fund's operating expense ratio and thus represent what can be, in high-turnover portfolios, a significant additional expense that reduces investment return.