What Is Commercial Mortgage Backed Securities

A commercial property can be expensive to buy or refinance. So instead of one lender holding a loan for years, some loans get packaged and sold to investors as a tradeable fixed-income product. That “package” is what people mean when they ask what is commercial mortgage backed securities.

What is a commercial mortgage-backed security?

A commercial mortgage-backed security (CMBS) is a fixed-income investment backed by mortgages on commercial properties—not homes.

In plain terms, a CMBS is a type of debt security. Its value is tied to the cash flows (the money coming in) from commercial real estate mortgage loans. Those mortgages come from loans made to buy, refinance, or improve income-producing commercial properties.

A helpful way to think about it:

• A mortgage loan is the original deal between a borrower and a lender.
• A CMBS is the investment that gets created using those mortgage loans, often after they’ve been bundled (grouped together) and sold.

What does “commercial” mean here?

In this context, “commercial” usually means property types like offices, retail centers, industrial buildings, and other income-producing real estate. Residential properties are a different category.

How commercial mortgages become CMBS

Here’s the connection that explains why CMBS exist.

Step-by-step: from property mortgage to security

1. A lender makes a commercial mortgage loan

• The loan is tied to a specific commercial property.
• The loan terms are set up so borrower payments support the structure of the deal.

1. The loan is structured to be securitized

• Securitized means the loan is organized into a pool that can be turned into an investment security.
• A CMBS loan program is designed to support that “turn into a security” path.

1. Multiple loans get bundled

• Instead of one property loan sitting alone, several commercial mortgage loans may be grouped together.

1. The pooled mortgages back the CMBS sold to investors

• Investors buy the resulting CMBS debt securities.
• The CMBS is backed by the cash flows from the underlying commercial mortgage loans.

1. The secondary market trades the security

• After issuance, the CMBS can be bought and sold in the secondary market (trading after the initial sale).

Where CMBS loans fit for borrowers

A CMBS loan is not the same thing as the final investment. It starts as a commercial mortgage loan made on a property, but it’s often created as part of a process that ends with a security being sold.

Some CMBS loan programs can provide non-recourse, fixed-rate financing for income-producing commercial real estate. (“Non-recourse” generally means the lender’s primary remedy is the collateral property rather than pursuing the borrower personally, but terms can vary, so you should check the loan agreement.)

How CMBS loans differ from CMBS securities

This is where confusion is common because the names are close.

CMBS loan = money for the property

A CMBS loan is the mortgage made to the borrower on a commercial property. It’s a real-estate financing product.

CMBS security = the investment created from loans

A CMBS security is the fixed-income investment that investors buy. It’s backed by the cash flows from commercial mortgage loans, usually from a pool of them.

The relationship

• The loan is what happens at the property level.
• The security is what happens at the investor level.
• The security is built from the loan(s), then sold in the market.

That’s the central idea: the commercial mortgage and the CMBS are linked, but they serve different parties.

A simple commercial mortgage-backed securities example

Here’s a made-up but realistic flow, just to show the structure.

• A shopping center owner wants financing to refinance.
• A lender offers a commercial mortgage loan secured by the shopping center.
• That loan is part of a larger CMBS loan program, designed so it can be packaged and sold later.
• Over time, other commercial property loans, such as offices, industrial buildings, and retail, are bundled into a pool.
• Investors then buy CMBS debt securities backed by the cash flows from that pool of commercial mortgages.
• After the securities are first sold, they can trade in the secondary market.

In this example:

• The property borrower focuses on getting mortgage terms approved and understanding repayment obligations.
• Investors focus on how the underlying mortgages are likely to perform and generate cash flow.

CMBS versus MBS: the key difference

People also ask: What’s the difference between CMBS and MBS?

Same “big idea,” different underlying property

Both are mortgage-backed securities, meaning they’re backed by mortgage loans. The difference is what the mortgages are secured by:

• CMBS are backed by mortgages on commercial (and often multifamily) real estate properties.
• MBS generally refers to mortgage-backed securities backed by residential real estate.

So, the “what’s under the hood” differs: commercial property cash flows versus residential mortgage cash flows.

Why that matters

Commercial real estate and residential housing can respond differently as markets change. That doesn’t automatically make one “better,” but it does mean the underlying mortgage pools are different. That can change the borrower base, property income drivers, and loan characteristics.

How investors and commercial property borrowers use CMBS

CMBS comes up for different reasons depending on which side you’re on.

For investors (fixed-income buyers)

Investors may use CMBS as a fixed-income product tied to commercial real estate mortgage cash flows. In other words, they’re buying an investment where the income stream depends on mortgage payments from commercial properties.

Because CMBS are structured as debt securities, investors typically review the underlying mortgage pool and the security structure when deciding whether to buy.

For commercial property borrowers (getting financing)

Borrowers use the loan side of the CMBS market to fund real estate needs like acquisition or refinancing. In some cases, CMBS loan programs can provide non-recourse, fixed-rate financing for income-producing commercial properties.

From a borrower’s perspective, the appeal often comes from matching the loan structure to how the property generates income, but the fit depends on the specific loan terms offered.

CMBS loans versus traditional bank loans

Here’s a comparison that keeps the loan-to-security idea in view.

Traditional bank loan

• A bank makes a loan to the borrower.
• The bank typically holds the loan (or services it) instead of turning it into a packaged security right away.
• The borrower works mainly through that lender relationship.

CMBS loan

• A commercial mortgage is made on a property with the end goal of being structured for securitization.
• The loan is part of a program where loans can be bundled and sold to investors as CMBS.
• The borrower’s mortgage is connected, indirectly, to a broader investor-backed capital market product.

A key takeaway

With a CMBS loan, you’re not only borrowing from a bank. You’re part of a process that can end with a security backed by mortgage cash flows, which then gets sold into the secondary market.

The main difference is what happens after the mortgage gets originated.

What to check before evaluating a CMBS investment or loan

Whether you’re looking at CMBS as an investor or evaluating a CMBS-style financing option as a borrower, your main goal is the same: understand what really backs the money flow.

Here’s a checklist-style guide you can use to ask better questions.

If you’re evaluating a CMBS investment

• What commercial mortgage loans back the security?

Look at the property types and the loan pool the CMBS is built from.

• How is the CMBS structured as a debt security?

Since CMBS are debt securities, the legal and payment structure matters.

• Where does the cash flow come from?

The CMBS is backed by cash flows from commercial real estate mortgages, so look at what drives those payments.

• What does the secondary market context mean for liquidity?

CMBS can trade after issuance. If you might sell, you’ll want to understand how trading works for the specific product you’re considering.

You may also see discussion of the commercial mortgage-backed securities delinquency rate online. But that term is product-specific: delinquency rate is one input, and it needs to match the exact CMBS deal or loan pool you’re looking at. Don’t treat a generic number as a direct answer to “how safe is this CMBS?”

If you’re evaluating a CMBS loan as a borrower

• Is the financing actually non-recourse and fixed-rate (if that’s what you want)?

“Non-recourse” and “fixed-rate” are major terms. Confirm them in the loan documents.

• How does the structure work with your property’s income?

Since CMBS cash flow comes from mortgage payments, make sure your repayment plan fits how the property earns money.

• What fees and requirements come with securitization-driven loan programs?

CMBS loan programs can use different steps than a standard bank loan. Ask about timelines, documentation, and any conditions you must meet.

• What happens if circumstances change?

The loan terms control outcomes. Read the agreement closely and don’t rely on assumptions.

A quick FAQ you’ll likely run into

What’s the difference between CMBS and MBS?

CMBS are backed by mortgages on commercial properties (and often multifamily). MBS generally refers to securities backed by residential mortgage loans. Both are mortgage-backed securities, but the underlying property type differs.

What about risk and returns—how do I think about them?

The facts above explain what CMBS are and how they’re backed. They don’t spell out specific risk categories or guaranteed return profiles, so you’ll need to evaluate the deal documents for the specific offering and, ideally, talk with qualified professionals.

Before you act

If you’re comparing CMBS loans vs bank loan options, or you’re evaluating a CMBS as a fixed-income investment, use the loan-to-security connection as your anchor: the commercial mortgage loan is the root, securitization is the bridge, and the investor security is where the end product lives.

Compare your own situation to the checklist above. If you’re considering a financing decision or an investment decision, get help from qualified professionals who can review the specific terms and documents in front of you.