What it means
When a bank bundles thousands of loans into a pool and sells bonds backed by them, buyers want a single number that describes how much time is left. Some loans in the pool will be nearly paid off while others have decades to run, so a simple average of their terms would mislead.
WART weights each loan by its remaining balance so that large loans count for more. In the mortgage-backed securities market, remaining term is usually reported alongside two companions.
The weighted average coupon (WAC) shows the typical interest rate, and the weighted average loan age (WALA) shows how long the loans have been outstanding. Together the three give a quick profile of the pool, and you will often see WAM and WART used interchangeably for the remaining-term figure.
The number matters because it sets the outer limit on how long investors will be paid. A pool with a WART of 330 months is a long-dated asset, so its value reacts more strongly to interest rate changes than a pool with a WART of 48 months.
Lenders and investors therefore compare it with the maturity of the bonds they issue or hold. WART is a contractual measure, so it assumes every borrower pays on schedule and nobody prepays.
In real life borrowers refinance, sell homes or pay early, which makes the actual life of the pool shorter. Analysts add prepayment assumptions on top of WART to estimate the weighted average life.
Business users meet WART when valuing loan books, buying receivables, or setting up funding lines against a portfolio. A lender who funds a pool with 3-year borrowings when the WART is 25 years has created a timing mismatch that will need refinancing.
Spotting that mismatch early is the practical benefit of the metric.
In practice
Real-world examples.
Example
An investment fund considers buying bonds backed by a $10,000,000 pool of home loans. The offering document shows a WART of 297 months, so the analyst knows the pool is a long-dated asset and sizes the position with that interest rate sensitivity in mind.
Example
A car finance company funds its loan book with a bank facility that expires in 3 years. The loan book has a WART of 52 months, so the treasury team arranges a renewal well before expiry to avoid being forced to sell loans in a hurry.
Example
A small business lender is selling a pool of equipment loans to a larger bank. The buyer values the pool using a WART of 36 months and asks for a lower price when it discovers that the figure was calculated before several large loans were added.
Formula
Calculation
WART = sum of (outstanding balance of each loan x remaining months of that loan) / total outstanding balance
Suppose a pool has three groups of loans. Group A is $2,000,000 with 300 months left, group B is $5,000,000 with 330 months left and group C is $3,000,000 with 240 months left. The total balance is 2,000,000 + 5,000,000 + 3,000,000 = $10,000,000. The weighted months are (2,000,000 x 300) + (5,000,000 x 330) + (3,000,000 x 240) = 600,000,000 + 1,650,000,000 + 720,000,000 = 2,970,000,000. WART = 2,970,000,000 / 10,000,000 = 297 months, which is 24.75 years.Case study
Seen in the real world.
Cedarbrook Lending is an illustrative, fictional consumer lender that packages $60,000,000 of loans into bonds each year. In one deal the team quoted a WART of 54 months, based on loans that had all been originated in the last quarter.
During due diligence, a buyer asked for the figure to be recalculated using the latest balances. Because several older loans had been paid down and a few large new loans had been added, the true WART came out at 49 months.
The five-month difference changed the expected cash flow profile and led the buyer to ask for a small price reduction. The illustrative lesson is that WART must be refreshed with current balances, since stale weights give a misleading picture of a moving pool.
Watch out
Common mistakes.
- Weighting by the number of loans rather than by outstanding balance, so a handful of small loans distorts the result.
- Using the original loan term instead of the remaining term, which overstates how long the pool has left.
- Treating WART as the expected life of the bonds when prepayments usually make the real life shorter.
Questions
People also ask.
What is the difference between WART and WALA?
WART measures how many months are left on the loans, while WALA measures how many months have already passed since they were made.
Does WART fall every month?
Yes, because each month of scheduled payments reduces the remaining term by one month, although adding new loans to a revolving pool can push it back up.
Is WART the same as weighted average life?
No, because weighted average life measures the average time until each dollar of principal is repaid, whereas WART simply averages the contractual end dates.
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