By
Nikita Bundzen Head of North America Fixed Income Department
Updated January 13, 2025
What is the Pool Factor?
Pool factor represents the proportion of the original loan principal remaining in an asset-backed security (ABS). Expressed as a numerical coefficient ranging from zero to one, it serves as a measure of the outstanding balance relative to the original face value of the security. As payments are made on the underlying mortgages, the pool factor gradually decreases over time, indicating the gradual repayment of the loans. This metric is particularly relevant in the context of mortgage-backed securities (MBS), where pools of mortgages are bundled together and sold to investors. Understanding the pool factor helps investors assess the remaining value within the security and evaluate the risk associated with potential changes in loan repayment dynamics.

How Pool Factor Works
Pool factor works by providing investors with insight into the remaining balance of the original loan principal within an asset-backed security (ABS). Calculated by dividing the outstanding principal balance by the original principal balance, this numerical coefficient ranges from zero to one. Initially set at one when the security is issued, the pool factor gradually decreases as payments are made on the underlying mortgages. This reduction reflects the repayment of loans over time, allowing investors to track the progress of loan repayments and assess the risk associated with changes in repayment patterns.
Example of Pool Factor:
Initial Issuance:
After Repayments:
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Over time, borrowers in the mortgage pool make payments, reducing the outstanding balance.
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If $40 million of the principal has been repaid, the remaining balance is $60 million.
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The pool factor is calculated as: Pool Factor=Remaining Principal/Original Principal=60/100=0.6
Interpretation:
Importance of Pool Factor in Asset-Backed Securities (ABS)
In assessing the performance of a mortgage-backed security (MBS), investors closely scrutinize various factors, including loan payments and mortgage payments, which directly impact the cash flows generated by the underlying mortgage loans. Understanding the weighted average coupon of the mortgage-backed security (MBS) and its relationship to the fair market price is important for bond investors seeking to optimize their investment portfolios. By analyzing the pool factor alongside other key metrics, investors can make informed decisions about purchasing or selling mortgage-backed securities issued by government agencies or private entities, thus navigating the complexities of the bond market, whether asset-backed or corporate bond options, with greater confidence.
The pool factor serves as a tool for investors in evaluating the expected cash flows and duration of ABS investments. A higher pool factor indicates a larger remaining balance of the original loan principal, suggesting a longer investment horizon and more stable cash flows. Conversely, a lower pool factor may signal accelerated loan repayments and shorter investment durations, which can impact the yield and risk profile of the ABS. By incorporating the pool factor into their investment analysis, investors can make more informed decisions regarding portfolio allocation and risk management strategies in the asset-backed securities.
Role of Government Agencies in Publishing Pool Factors
Government agencies play a significant role in the financial market by publishing pool factors for mortgage bonds in the United States. These agencies, including Freddie Mac, Fannie Mae, and Ginnie Mae, release pool factor data on a monthly basis, providing investors with transparent and standardized information on the performance of mortgage-backed securities (MBS). By publishing pool factors, these government entities ensure market transparency and facilitate informed decision-making among investors, allowing them to track the remaining balance of the original loan principal within MBS and assess the associated risks. Example: FR SD8267 Bonds, 5% 1nov2052, USD (ABS) (US3132DWFG33)
Moreover, the involvement of government agencies in publishing pool factors adds credibility and reliability to the data, enhancing investor confidence in the mortgage bond market. Investors rely on this data to evaluate the performance and value of MBS investments, as well as to monitor changes in loan repayment dynamics and prepayment characteristics. By providing timely and accurate pool factor information, government agencies contribute to the efficiency and stability of the mortgage bond market, fostering greater trust and liquidity among investors.