Welcome to The S-Curve
Now you will be able to receive the latest announcements, product updates, and our insights on the mortgage market in real time.
The name of the blog, the S-Curve, is a reflection of our logo and the central feature of our prepayment model. S-curves are seen in nature in many phenomenon, from population growth to prepayment and default models. Our first S-curve, in the early 1990s, used the arctangent function, then piece-wise linear functions, and evolved over time to be more complex and vary by FICO, loan size and LTV. This evolution encapsulates both the timeless nature of fundamental relationships and constant innovation to describe them better over time.
We hope you find the information useful and we look forward to your feedback.
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Ability-To-Repay Benchmark UpdateThoughts
Summary
In 2021, Andrew Davidson & Co. Inc. (AD&Co) proposed a benchmark cohort approach to setting Ability-to-Repay (ATR) Qualified Mortgages (QM) standards. Successful benchmarks based on data are model-free and transparent, and the cohorts must perform consistently in comparison to one another and across time. Our original work used data through the early stages of the pandemic when non-performing loan percentages skyrocketed. This update shows that the cohorts continue to perform consistently.
To review; the metric is 60+ DQ (delinquency) rates at 24 months old for loans guaranteed by GSEs, FHA, VA, and non-QM securitizations. We update performance through late 2021 or early 2022 depending on the data source. The update turned out to be six to nine months past the peak non- performance rates (60+ DQ + Forbearance) of the pandemic. One of the best tests of reliability are cohorts that perform consistently at significant turning points. We show two different examples of cohort performance which all pass with flying colors.
Figure 1 extends the original time-series delinquency graph by cohort across combined federal segments (GSE, FHA, VA) and shows consistent performance through the two sharp turning points in delinquencies from the lows before the pandemic and the peak thereafter.
Figure 1. Delinquency Rates by Cohort
Figure 2 extends the time-series graph that compares the ‘FHA Average’ cohort for each of the three federal segments, GSE, VA, FHA, and non-QM. The ‘FHA Average’ cohort is roughly 95 LTV, 680 FICO, 40 DTI for government lending, and about 90 LTV, 680 FICO for non-QM. The results continue to illustrate that the benchmark cohorts perform consistently across market segments.
Figure 2. Delinquency Rates for ‘FHA Average’
Conclusion
The pandemic and the federal response to it are unprecedented in modern times for their impact on the US economy and housing market. Nevertheless, mortgage cohorts performed consistently over the last several years across federal and non-QM segments, increasing confidence in this approach. This stability contrasts with the vastly higher non-performance rates of the subprime and reduced documentation era that resulted from poor lending practices, as we reported in the original study.
This highlights that conscientiously measuring income is essential to consistency.
The S-Curve Archives
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EventsAndrew Davidson & Co., Inc (AD&Co) proudly sponsored IMN’s 11th Annual Mortgage Servicing Rights (MSR) Forum by Informa at the New York Hilton Midtown. Senior modeler Daniel Swanson joined the “Managing Delinquencies & Forbearance Value” panel in discussing how servicers are adapting to today’s market and the evolving delinquency trends.
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PodcastTune in to our fourth episode of AD&Conversations with Kevin Lin and Eknath Belbase, our product lead for our Climate model. In this episode, they discuss the new Climate Impact Suite (CIS) pilot project, and Belbase outlines several challenges the team is navigating, including:
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Podcast
Tune in to our fourth episode of AD&Conversations with Kevin Lin and Eknath Belbase, our product lead for our Climate model. In this episode, they discuss the new Climate Impact Suite (CIS) pilot project, and Belbase outlines several challenges the team is navigating, including:
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Podcast
Andrew Davidson was invited to speak on Equifax's Market Pulse Podcast titled, "Driving Efficiency and Resilience in the Mortgage Industry" live at the 2025 MBA Annual Convention in Las Vegas.
Andy explains how variations in data files can distort risk assessment, creating a dual risk for lenders: extending credit to borrowers more likely to default while overcharging customers whose risk is overstated.
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ThoughtsOur latest Policy Perspective written by Richard Cooperstein offers an analysis of the U.S. housing and mortgage finance markets, focusing on key trends and forward-looking risks. While housing markets are not fully efficient, they do respond to economic imbalances which create opportunities and vulnerabilities. This article explores how demographic shifts, credit access, interest rates, and climate risks shape both housing demand and supply.
Key findings include:
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Podcast
Join Kevin Lin in a conversation with Richard Cooperstein as they dive into Kinetics, AD&Co's modular platform designed to deliver the full power of our models and analytics; with the flexibility to license only the tools you need.
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Thoughts
The latest Policy Perspectives paper “Competing Claims in Privatization of Fannie Mae and Freddie Mac” is now available!
Nearly 20 years ago, on September 6, 2008, the GSEs, Fannie Mae and Freddie Mac entered conservatorship. Since that time there have been many proposals to restructure, eliminate or release the GSEs. Once again there is talk about the privatization of Fannie Mae and Freddie Mac.
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ThoughtsAD&Co held our annual employee meeting in Detroit, Michigan. In addition to gathering everyone in person to socialize and strategize, we use these annual meetings to learn about different cities, especially with regard to housing market dynamics.
We chose Detroit because the oft-maligned city is undergoing a significant renaissance, and we wanted to explore the area and learn how housing may have played a role in both Detroit’s decline and rebirth.
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ProductsAndrew Davidson & Co., Inc (AD&Co) is pleased to announce the beta release of MARS+, the next generation of Mortgage Analysis & Reporting System (MARS), which has been in use since 2008 for performance reporting of AD&Co models. MARS+ aims to provide enhanced and advanced capabilities and features for mortgage analysis and reporting.
The new enhancements of MARS+ include:
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EventsSeveral AD&Co employees attended SFVegas 2025. This post shares their unique perspectives from attending the conference and key takeaways from the sessions.