What term refers to the proportion of total fund assets that are traded in a year?

The term that refers to the proportion of total fund assets that are traded in a year is known as the turnover rate. This metric provides insight into the trading activity of a fund, indicating how frequently assets within the fund are bought and sold over a specific period. A high turnover rate may suggest an active management strategy where the fund manager frequently adjusts the portfolio, while a low turnover rate typically points to a more passive investment approach, where holdings are maintained for longer durations.

In contrast, net asset value (NAV) represents the total value of a fund’s assets minus its liabilities, and is crucial for determining the price at which shares of the fund are bought and sold but does not indicate trading activity. Yield is a measure of the income generated by an investment, usually expressed as a percentage of its current price, and does not relate to trading volume or activity. The expense ratio quantifies the costs associated with managing a fund, expressed as a percentage of the fund's assets, but does not reflect turnover or trading practices.

Thus, the turnover rate serves as a specific measure of trading frequency, making it the correct term in this context.