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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Mortgages at SFVegas 2023EventsThe Structured Finance Association hosted SFVegas 2023 (February 26 - March 1), a broad capital markets conference with thousands of attendees in Las Vegas. Andrew Davidson & Co. Inc. (AD&Co) was a sponsor focused on the mortgage sector. As we engaged with clients and policy leaders, a few themes emerged: Data, Expanding Access Safely, Ginnie Mae Servicing and Auto Loan Performance.
Data
Well-managed data is the underpinning of well-run mortgage organizations, supporting efforts to manage risk, profitability, and compliance. Data is essential to developing new products, improving accuracy, and expanding access to mortgage finance. Nearly everyone we spoke to spends time and money on data and still struggles to manage it through their internal operations, from loan level acquisition to portfolio management and reporting. They expend additional effort to acquire and pass on data in the larger mortgage ecosystem. The richness and reliability of data degrade even within companies, let alone as mortgage-related assets pass through the value chain. This degradation worsens the information asymmetry between sellers and buyers, increasing risk and pushing the mortgage business further from an efficient market. It impedes adding new data to the data-frame, such as the new Trended Credit Scores or expanded data generally, that helps expand markets.
These realities align with the economic theory of imperfect markets and utilities. Markets that provide gains from scale and consistency have attributes of public utilities. Adding privacy concerns and positive systemic value beyond individual mortgage transactions do as well. Reducing the inherent information asymmetry between sellers and buyers further suggests that the efficient market outcome could be a regulated market utility of loans and related data. Data aggregators can supply to the utility, and data consumers can access it.
Expanding Access Safely
Safely expanding access to mortgage finance is not automatic. The legacy of discrimination generally and in housing finance specifically, shows up in the persistently lower homeownership rates of minority populations. Homeownership rates can be expanded temporarily by lowering standards and raising risk, or durably by using new data that lowers risk. Making progress requires commitment and solving the data market failure described above.
Ginnie Mae Servicing
It’s well known that compliantly servicing non-performing loans can cost several times the fixed servicing fee and thus pose systemic risk. During the Pandemic, Federal agencies scrambled to provide financing and reduce the burden on non-bank servicers that represent a substantial majority of the Ginnie Mae market without the federal backing that most of the mortgage ecosystem enjoys. This cost-revenue imbalance is not an advancing issue and cannot be solved by transferring the burden of advancing NPL payments to bond holders. The market bid for Ginnie Mae servicing in mid-2020 was zero because of the expectation of high NPL rates. Fortunately, record low mortgage rates and record refinancing volume provided servicers who were also originators with cash flow to offset the cost of servicing FHA NPL rates that temporarily reached 14%. The next time there is a systemic rise in delinquency rates, this extra cash flow is unlikely.
What’s the solution for this? The most straightforward solution is a variable servicing fee that aligns revenues with expenses, but there is surprisingly little enthusiasm for this solution. Ginnie Mae’s leadership is clearly aware of the systemic risk potential and is seeking a solution. The U.S. mortgage market often uses a federal backstop behind private financial markets to provide the stability the economy depends on. The backstops of deposit insurance or for the GSEs are examples. We will be studying this issue.
Auto Loan Performance
For the first time in awhile, attention is being paid to rising auto loan delinquency rates, both prime and subprime. Ordinarily, today’s historically low unemployment rate would associate with low delinquencies, so this rise is worrisome. It’s well-known that supply-chain disruptions during the Pandemic caused spikes in new and especially used car prices. Cars financed at those high prices pose more risk, and used car prices have already dropped about 15% from their peak. AD&Co will be monitoring this performance and refining our models.
The S-Curve Archives
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ThoughtsRecently, 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.
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PodcastJoin 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
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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.
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ThoughtsBuilding 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.
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EventsAndrew 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.”
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EventsAD&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.
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NewsAD&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.
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ThoughtsIn 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.
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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.
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ThoughtsThere 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.