Bond fund
A fund invested in debt securities. Unlike a single bond it has no maturity date: the term does not approach, it is maintained at a constant level.
How to read the number
Hence the different behaviour: there is nothing to hold to maturity, the unit value moves with the prices of the issues, and coupons arrive inside the fund and lift the calculated price.
When the metric lies
There is no promise to return a face value here. When rates rise a fund with long duration falls and works the loss back through a higher coupon not at once, but over a time comparable to its duration.
Also known as: fixed income fund