It stands for yield-to-average life; the yield which is calculated using the point at which half of the bonds (known as sinking fund bonds) in the issue will have been redeemed or called in (this point is known as the intermediate point). Sinking fund bonds have a specific maturity and are subject to a random call before they reach maturity date. Such bonds (whether corporate, municipal, or mortgage) use random selection (lottery) to select some of them for retirement at regular intervals. In calculating this yield, cash flows are usually assumed to be reinvested at a similar interest rate as they are called in.
This yield is also known as a yield to the intermediate point.
