The S-Curve

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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Blog - Latest
  • Why Financial Firms Need a New Climate Change Risk Strategy Starting Now

    Eknath Belbase

    Thoughts

    According to a report by the Research Institute for Housing America, climate change risk is rapidly increasing in the housing industry and will continue to demand more attention and regulation in the near future.

    Climate change will impact risk factors in the housing industry in nearly every corner of the globe. Wildfires are becoming more common and the area they ravage more extensive. Hurricanes and severe storms are happening with more frequency and severity. Potential damage from excess heat and droughts elevates risk to properties every day.

    However, flooding is currently one of the highest risk factors posed to the housing industry. Many housing areas are used to the idea of flood risk and are adequately prepared and protected, but many properties that were never at risk before are now in the danger zone. The housing market is currently in a vulnerable position.

    When Floods Outpace Insurance Policies

    Depending on geography, more properties without previous flood risk are increasingly likely to experience flood damage. Homes and communities that were erected in floodplains are used to the protocols: Safety procedures such as evacuating or securing the area, working with insurance to cover damage, or receiving aid to rebuild when possible.

    Under the National Flood Insurance Program, homes that are federally backed by programs such as Freddie Mac and Fannie Mae in certain areas require the owners to carry flood insurance. Those homes are located in floodplains that are defined based on a 100-year flood probability.

    The problem is that floodplain boundaries are rapidly changing. One hundred years' worth of flooding data is not as relevant as it used to be when flooding zones are becoming more and more volatile. Even as the area of potential flooding damage overflows into neighboring regions, the floodplain boundaries have not been redrawn recently enough to impact flood policy uptake.

    That means many homes that are at risk of future flooding are not likely or required to carry flood insurance. Experts are predicting that the National Flood Insurance Program will be stretched to its limits very soon, and that banking and insurance regulation will need to act quickly to spread and manage climate-related risk. It's possible that soon, the total cost of owning homes will outpace the value of the home.

    This becomes very concerning when we consider the likelihood of mortgages going unpaid; a lack of flood insurance then quickly becomes not just a housing risk but a credit risk for the owners and an economic risk for the country if housing prices plummet and people’s debts begin to far outvalue their assets.

    Updating Risk Calculations on Climate Change Analysis

    Firms currently vary in their preparedness to face climate change insurance risk. As data becomes more advanced, some firms have begun to license property-level climate risk data, and specialist analytics firms are appearing with expertise in climate models.

    The Fed and the SEC are also trying to adapt regulations to fit the new (and ever-changing) reality of climate change risk. There are new committees dedicated to assessing climate change analysis and determining systemic risk to the entire financial world, including the Supervision Climate Committee. These regulators will need updated methods to quantify risk and mandate disclosure, but for now, changes are nascent and firms will have to add their own experience to the bank of loss exposure research.

    Financial firms are facing — or are about to face — considerable pressure from investors, governing and regulatory bodies, and insurance and banking regulators concerning the way they calculate risk. They will probably also feel some pressure from employees and workers in the financial sector, who are becoming increasingly alarmed about the impending disruption of climate change.

    Firms will need to manage climate risk alongside their broader risk management strategy. For that to work, they’ll need to understand climate change data and the set of exposure scenarios that are relevant to them. For example, McKinsey predicts that about one-third of the planet's land will be affected by climate change. In addition, flooding exacerbated by climate change is expected to double the damage to capital stock by 2030.

    Financial institutions urgently need to understand how to calculate and explain the risks posed by climate change, both for their own risk management strategies and for stakeholders. Quantifying climate change risk will be an evolving science. Property portfolios will require new risk scores based on the potential hazards that climate change will bring. Those scores will then need translating into commonly used financial measures, such as credit risk, market risk and prepayment risk.

    As financial firms wait for regulatory approaches to become clear, they will need to continue to educate themselves and to remember that climate change models will shift rapidly — the best climate change risk strategy will be the one that is most able to change.

Blog - Archives

The S-Curve Archives

  • Mickey Storms, Alex Levin

    Thoughts

    Recently, aggregators have crossed market borders by issuing residential mortgage-backed securities (RMBS) backed by owner-occupied (OO), GSE-eligible conforming loans. Additionally, conforming mortgage loans have drawn investment interest from insurance companies fronted by aggregators and evaluated by third-party firms. These developments constitute historically rare disintermediations of the nearly monopsonist purchases of conforming loans by the GSEs.

  • Rob Landauer, Abe Martin

    Podcast

    Join Rob Landauer in a conversation with Abe Martin as they discuss his recent Pipeline article, "Modeling the Balance Behavior of HELOC Borrowers." In this episode, they highlight key points from the article as he shares insights into the draw component of HELOCs and provide an update on the beta rele

  • Ashlea Bonds

    News

    We’re excited to announce a major addition to the Andrew Davidson & Co., Inc. (AD&Co) team. Industry leaders Kelli Sayres and Gene Park, known for building and scaling leading fixed-income analytics platforms, have joined AD&Co’s Business Development team.

  • Sanjeeban Chatterjee, Vivian Li, Joni Baker, Richard Cooperstein

    Thoughts

    Building on our earlier research on expanded consumer attributes, AD&Co continues to explore how credit data contributes to modeling delinquency and prepayment risk, which are key drivers of mortgage servicing rights cash flows and valuation.

  • Joann Gollette

    Events

    Andrew Davidson recently joined NFM Lending’s Greg Sher on the One On One podcast to discuss our recent white paper, “The Impact of Moving Away From the Tri-Merge Standard.”

  • Eknath Belbase, Daniel Swanson, Yvonne Chen

    Events

    AD&Co recently sponsored and attended SFVegas 2026 and Optimal Blue Summit 2026. This post shares the AD&Co team's unique perspectives and key takeaways from attending both conferences.

  • Alex Levin

    News

    AD&Co US Mortgage High Yield Indices

    The Federal Reserve Economic Data (FRED) portal, housed by the Federal Reserve Bank of St. Louis, has been publishing AD&Co’s CRT indices since 2019. These series posted under the overall name of “US Mortgage High-Yield” include total return rates and credit and option-adjusted spreads (crOAS) – a projected return’s spread over Treasury (in the past, Libor). These series are available going back to 2014-end and tiered by CRT initial supports.

  • Joni Baker, Sanjeeban Chatterjee, Richard Cooperstein, Andrew Davidson

    Thoughts

    In July 2025, the US Federal Housing Finance Agency (FHFA) announced that the government-sponsored entities (the Enterprises or GSEs), Fannie Mae and Freddie Mac, would permit lenders to choose between Classic FICO and VantageScore 4.0 credit score models for loans sold to the GSEs. FHFA also stated in a social media post that the tri-merge standard would be maintained for mortgage underwriting. Nevertheless, some mortgage industry stakeholders recommend moving away from the tri-merge standard for GSE mortgages in favor of a single or bi-merge report standard.

  • Joann Gollette

    News

    As housing faces more climate threats that result in more losses, the insurance program that it sits on is teetering on the brink of collapse. Yet, the home insurance market has three distinct stakeholders that have competing priorities, and today, there is no motivation for a collaborative solution.

    Understanding how to strengthen and protect the current structure requires looking at the cost burdens along with the risk for each of those parties.

  • Sanjeeban Chatterjee

    Thoughts

    There has been a flurry of activity in the mortgage markets since the 2018 passage of the Economic Growth, Regulatory Relief, and Consumer Protection Act. This act requires the Federal Housing Finance Agency (FHFA, now known as US Federal Housing) to validate and modernize the credit score models used in the housing finance system. It should be noted that so far, the discourse has been around mortgages sold to the Enterprises (Fannie Mae and Freddie Mac). Ginnie Mae has not provided any guidance on their plans to start using new credit score models.