Weighted average life
Weighted average life means the weighted-average time to the return of a dollar of principal, calculated by multiplying each portion of principal received by the time at which it is expected to be received (based on a reasonable and supportable estimate of that time) and then summing and dividing by the total amount of principal. The calculation of weighted average life for interest only securities means the weighted-average time to the return of a dollar of interest, calculated by multiplying each portion of interest received by the time at which it is expected to be received (based on a reasonable and supportable estimate of that time) and then summing and dividing by the total amount of interest to be received.