# Understanding Collateralized Mortgage Obligations (CMOs): A Comprehensive Guide

## What Is a Collateralized Mortgage Obligation?

A collateralized mortgage obligation (CMO) is a type of mortgage-backed security composed of a pool of bundled mortgages sold as an investment. Organized by maturity and risk level, CMOs provide cash flows from repayments on the underlying mortgages. Investors receive principal and interest payments based on predetermined agreements, yet the complex structure of these instruments makes them sensitive to changes in interest rates and economic conditions.

### Key Takeaways

*   A collateralized mortgage obligation (CMO) is a type of mortgage-backed security that organizes mortgages based on maturity and risk levels.
*   CMOs consist of tranches, which are categorized by risk profiles, maturity dates, and interest rates.
*   Investors in CMOs receive principal and interest payments influenced by the repayment behavior of the underlying mortgages.
*   During the 2008 financial crisis, CMOs gained notoriety due to their ties with subprime mortgages.
*   The risks associated with CMOs have prompted regulatory changes to mitigate potential financial instability.  
    

## How Collateralized Mortgage Obligations Operate

Collateralized mortgage obligations consist of several tranches, or groups of mortgages, organized by their [risk profiles](https://www.investopedia.com/terms/r/risk-profile.asp). Tranches usually have different principal balances, interest rates, maturity dates, and risks of repayment defaults. Collateralized mortgage obligations are sensitive to interest rate and economic changes, like foreclosure and refinance rates, and property sale rates. Each tranche has a different maturity date and size, and bonds with monthly coupons are issued for them. The coupon makes monthly principal and interest rate payments.

Imagine an investor with a CMO of thousands of mortgages. Their profit depends on whether the mortgages are repaid. If only a few homeowners default but most pay as expected, the investor recovers both principal and interest. In contrast, if thousands of people cannot make their mortgage payments and go into foreclosure, the CMO loses money and cannot pay the investor.

Investors in CMOs, sometimes referred to as [Real Estate Mortgage Investment Conduits](https://www.investopedia.com/terms/r/real-estate-mortgage-investment-conduit-remic.asp) (REMICs), want to obtain access to mortgage cash flows without having to originate or purchase a set of mortgages.

## Comparing CMOs and CDOs: Key Differences and Similarities

Like CMOs, [collateralized debt obligations](https://www.investopedia.com/terms/c/cdo.asp) (CDOs) consist of a group of loans bundled together and sold as an investment vehicle. However, whereas CMOs only contain mortgages, CDOs contain a range of loans such as car loans, credit cards, commercial loans, and even mortgages. Both CDOs and CMOs peaked in 2007 just before the global financial crisis, and their values fell sharply after that time. For example, at its peak in 2007, the CDO market was worth $1.3 trillion, compared to $850 million in 2013.

> **Important**
>
> Organizations that purchase CMOs include hedge funds, banks, insurance companies and mutual funds.

## The Role of CMOs in the 2008 Financial Crisis

First issued by Salomon Brothers and First Boston in 1983, CMOs were complex and involved many different mortgages. For many reasons, investors were more likely to focus on the income streams offered by CMOs rather than the health of the underlying mortgages themselves. As a result, many investors purchased CMOs full of subprime mortgages, adjustable-rate mortgages, mortgages held by borrowers whose income wasn't verified during the application process, and other risky mortgages with high risks of default.

The use of CMOs has been criticized as a precipitating factor in the 2007-2008 financial crisis. Rising housing prices made mortgages look like fail-proof investments, enticing investors to buy CMOs and other MBSs, but market and economic conditions led to a rise in foreclosures and payment risks that financial models did not accurately predict. The aftermath of the global financial crisis resulted in increased regulations for mortgage-backed securities. Most recently, in December 2016, the SEC and [FINRA](https://www.investopedia.com/terms/f/finra.asp) introduced [new regulations](https://www.finra.org/sites/default/files/notice_doc_file_ref/Regulatory-Notice-16-31.pdf) that mitigate the risk of these securities by creating margin requirements for covered agency transactions, including collateralized mortgage obligations.

## The Bottom Line

Collateralized mortgage obligations (CMOs) are complex financial instruments that bundle mortgages into investment securities, organized by risk and maturity. Investors in CMOs should be mindful of their sensitivity to interest rate fluctuations and economic changes, which can significantly impact returns.

Despite their popularity and role in the 2008 financial crisis, CMOs offer a structured way to invest in mortgage flows, yet caution is advised due to the risk of default, especially in volatile markets. Always consider consulting a financial professional before engaging in investments involving CMOs or similar securities.