## What Is a Paydown Factor?

A paydown factor is calculated as the principal portion of a monthly loan payment divided by the original principal of the loan. Paydown factors can be calculated monthly and may be included in monthly statements. A paydown factor is also an important metric that is commonly observed when analyzing structured products.

### Key Takeaways

- A paydown factor is the percent of principal received relative to the original principal amount.
- This factor enables borrowers to better understand paydown rates.
- A paydown factor is commonly reported when analyzing structured products and mortgage-backed securities.
- The paydown factor provides an indicator for the level of principal being paid down across a structured credit product's portfolio and thus serves as a good measure of the performance of these investments.

## Understanding Paydown Factor

A paydown factor helps a borrower or investor gain an understanding of the paydown rates involved with various credit products. Borrowers can calculate a monthly paydown factor to analyze the principal being paid each month. A paydown factor is also an attribute that is commonly reported when analyzing structured products and specifically mortgage-backed securities (MBS).

## Paydown Factor Examples

Loans provide a basic example of calculating a paydown factor. Some lenders may include a borrower’s paydown factor in their monthly statements. The paydown factor shows the amount of principal paid in the previous month divided by the original principal value.

For example, a borrower with a $100,000 mortgage loan paying a 4% annual rate of interest over fifteen years will make monthly payments of $592. The amortization schedule factors in the borrower's 20% down payment and amortizes $80,000 over the life of the loan. In the first month, the borrower would pay approximately $267 in interest with a principal payment of $325. The paydown factor for the borrower’s first payment would then be $325 / $100,000, or 0.33%. As more of the principal is paid, the paydown factor increases.

### Structured Credit Products

Structured credit products typically include a portfolio of loans with varying credit qualities. Generally, these products will be comprehensively grouped by a target risk level based on the underlying credit qualities of the loans. The paydown factor can be a good metric for analyzing the performance of these investments since it provides an indicator for the level of principal being paid down across the portfolio.

Calculating the paydown factor for a portfolio of loans aggregates the calculation to include the total principal paid monthly, divided by the total comprehensive principal issued to borrowers.

Mortgage-backed securities commonly report paydown factors monthly. If the mortgage-backed security reports a steady paydown factor over time, then that is a good indication that the loans are not at high risk of delinquency or default. A significantly decreasing paydown factor can be a signal of increasing risk on the portfolio. If borrowers in the MBS are consistently reporting payment delinquencies, then a lower overall amount of the total portfolio principal will be paid down, and the paydown factor will show a significant decrease.

Ginnie Mae requires all mortgage-backed securities issuers to publish their paydown factors.