https://www.insurerbrain.com/w/index.php?action=history&feed=atom&title=Definition%3AMortgage-backed_securityDefinition:Mortgage-backed security - Revision history2026-06-13T13:29:04ZRevision history for this page on the wikiMediaWiki 1.43.8https://www.insurerbrain.com/w/index.php?title=Definition:Mortgage-backed_security&diff=9455&oldid=prevPlumBot: Bot: Creating new article from JSON2026-03-11T05:25:23Z<p>Bot: Creating new article from JSON</p>
<p><b>New page</b></p><div>📦 '''Mortgage-backed security''' is a fixed-income instrument created by pooling residential or commercial [[Definition:Mortgage | mortgages]] and selling tranched interests to investors — and it occupies a central place in the investment portfolios of [[Definition:Life insurance | life insurers]], [[Definition:Property and casualty insurance | property-casualty carriers]], and [[Definition:Reinsurance | reinsurers]] seeking predictable cash flows to match their [[Definition:Policy reserve | policy reserves]] and [[Definition:Claim | claim]] liabilities. Because insurance companies are among the largest institutional holders of mortgage-backed securities (MBS), the performance of these instruments has a direct bearing on carrier [[Definition:Solvency | solvency]] and [[Definition:Surplus | surplus]] levels.<br />
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⚙️ An MBS is structured by a [[Definition:Government-sponsored enterprise (GSE) | government-sponsored enterprise]] such as Fannie Mae or Freddie Mac, or by a private-label issuer, which purchases [[Definition:Mortgage | mortgages]] from [[Definition:Mortgage lender | originators]], groups them into pools, and issues securities backed by the principal and interest payments borrowers make each month. Investors receive pass-through cash flows, but face [[Definition:Prepayment risk | prepayment risk]] — when interest rates drop, borrowers refinance, returning principal earlier than modeled — and [[Definition:Credit risk | credit risk]], particularly for non-agency securities that lack a government guarantee. Insurers' [[Definition:Investment management | investment teams]] use [[Definition:Asset-liability management (ALM) | asset-liability management]] techniques to select MBS tranches whose duration and cash-flow profiles align with their liabilities, often favoring agency-backed issues for their lower [[Definition:Risk-based capital (RBC) | risk-based capital]] charges.<br />
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🛡️ The 2008 financial crisis laid bare how concentrated MBS exposure can cascade through the insurance sector. Carriers holding subprime and Alt-A tranches saw sharp mark-to-market losses, prompting rating downgrades and, in some cases, regulatory intervention. Since then, the [[Definition:National Association of Insurance Commissioners (NAIC) | NAIC]] has refined its treatment of structured securities within the [[Definition:Risk-based capital (RBC) | RBC]] framework, requiring insurers to model expected losses on a loan-level basis rather than relying solely on external credit ratings. This more granular approach, combined with tighter [[Definition:Investment policy | investment policy]] guidelines at individual carriers, has reshaped how the industry uses mortgage-backed securities — still as a core asset class, but with far greater scrutiny of underlying collateral quality and structural protections.<br />
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'''Related concepts:'''<br />
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* [[Definition:Asset-liability management (ALM)]]<br />
* [[Definition:Mortgage]]<br />
* [[Definition:Risk-based capital (RBC)]]<br />
* [[Definition:Prepayment risk]]<br />
* [[Definition:Credit risk]]<br />
* [[Definition:Collateralized debt obligation (CDO)]]<br />
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