Mezzanine debt and CMBS tranches are two different ways of slicing the risk on a commercial property, and they sit in different places. CMBS tranches are bond classes inside a trust that holds a pool of commercial mortgages, ranked from safest to riskiest and paid in that order. Mezzanine debt sits outside the trust as a separate loan, secured not by the building but by the borrower’s ownership interest in the entity that owns it. On a single property, both can be present at once: a CMBS senior mortgage at the bottom of the capital stack, a mezzanine loan layered above it, and equity on top.
Where Each Piece Sits in the Capital Stack
The capital stack for a large commercial property has a predictable shape. Senior debt is the primary mortgage, usually 60 to 75 percent of appraised value, with a first-priority lien on the real estate and the right to foreclose directly if the borrower defaults. When that senior loan is securitized, it becomes one of the mortgages in a CMBS pool.
Mezzanine financing fills 10 to 20 percent of the gap between the senior loan and the owner’s equity. It is junior to the senior mortgage in payment priority, which is why it costs more. Common equity sits on top, last to be paid and first to absorb losses.
The order matters because it determines who takes the hit when a property’s value falls. A senior lender can tolerate a meaningful decline before its principal is at risk. A mezzanine lender starts feeling pain much sooner. Equity can be wiped out entirely once losses chew through both the equity cushion and the mezzanine layer.
How CMBS Tranches Are Structured
When a lender pools dozens of commercial mortgages into a CMBS trust, the trust’s debt is carved into tranches, each with its own credit rating, coupon, and place in line. Rating agencies set those ratings based on default probability and expected loss severity for the underlying loan pool.
The senior tranche is rated AAA. It gets paid first and carries the lowest yield, but it also sits behind the thickest layer of protection: every tranche below it has to be wiped out before the AAA takes a dollar of loss. Pension funds and insurance companies are the natural buyers. Below that sit investment-grade tranches rated AA through BBB, each absorbing losses before the class above it and paying progressively higher coupons. Below investment grade are the BB and B tranches. At the very bottom is the unrated first-loss piece, the B-piece, which takes the first dollar of any loss. B-piece buyers negotiate aggressively and often kick individual loans out of the pool before a deal closes.
The riskiest tranches generally trade under Rule 144A, which restricts purchases to qualified institutional buyers. An institution has to own and invest on a discretionary basis at least $100 million in securities of non-affiliated issuers to qualify. Registered broker-dealers face a lower $10 million threshold. Banks must meet the $100 million test and carry an audited net worth of at least $25 million.1eCFR. 17 CFR 230.144A Private Resales of Securities to Institutions
Subordination: The Loss Buffer That Defines Each Tranche
Subordination is the mechanism that protects senior bondholders. If 30 percent of the deal’s bond classes sit beneath the AAA, the AAA has 30 percent credit enhancement, and the pool’s loans would have to lose more than 30 percent of total deal balance before AAA principal takes any hit. AAA tranches in a typical conduit CMBS have historically started around that 30 percent mark.
Lower in the stack, the buffer shrinks fast. A BBB- tranche might have only 3 to 5 percent of the deal absorbing losses beneath it, which is why it pays a much higher coupon and carries real default risk.
These levels move over the life of the deal. As loans pay down or get resolved after default, each tranche’s balance changes and effective subordination shifts. When a troubled loan is reappraised below its outstanding balance, the servicer calculates an appraisal reduction, which treats the expected loss as if it has already occurred and cuts into the notional balance of the most junior outstanding tranches. If a tranche’s balance is reduced far enough that way, it can lose its controlling-class voting rights, including the right to appoint or replace the special servicer.
How Mezzanine Debt Is Secured and Enforced
Mezzanine debt is structurally different from a CMBS loan in one critical respect: it is not secured by the real estate. The mezzanine lender takes a pledge of the borrower’s ownership interest in the entity that holds the property. If the borrower is an LLC that owns a shopping center, the mezzanine loan is secured by the membership interests in that LLC, not by the center itself.
That changes everything about enforcement. Equity interests are personal property, not real property, so the mezzanine lender’s security interest is governed by Article 9 of the Uniform Commercial Code. On default, the lender can dispose of the collateral after reasonable notice to the debtor and other parties with a recorded interest.2Legal Information Institute. UCC 9-611 Notification Before Disposition of Collateral A UCC foreclosure sale can be completed in weeks, where a judicial real estate foreclosure can drag on for a year or more. Speed is the mezzanine lender’s main structural advantage. Rather than wait out a court process, the lender takes control of the entity that owns the property and steps into the borrower’s shoes.
Pricing reflects the added risk. Mezzanine coupons commonly run 10 to 15 percent, compared to mid-single-digit rates on senior CMBS debt. Origination fees of 1 to 2 percent are typical. Documentation includes a promissory note and a pledge and security agreement, with a UCC-1 financing statement filed in the appropriate state to perfect the lien on the ownership shares.
Bad-Boy Carve-Outs
Mezzanine loans are almost always non-recourse, meaning the lender’s recovery is limited to the pledged collateral. The protection has exceptions, and the list has grown over the years. Certain acts by the borrower or its principals trigger full personal liability under what the industry calls bad-boy guaranties.
The classic triggers are fraud, misapplication of insurance or condemnation proceeds, waste of the property, and filing a voluntary bankruptcy petition. Modern loan documents have expanded the list to include unauthorized property transfers, environmental violations, failure to replace a property manager when required, and even negligence. Once a carve-out is triggered, the guarantor becomes personally liable for the full outstanding loan balance, converting a non-recourse obligation into full recourse. The difference between a narrow carve-out and a broadly drafted one can be millions of dollars in personal exposure, which is why borrowers’ counsel spend so much time negotiating the language.
The Intercreditor Agreement Between Senior and Mezzanine Lenders
Because the senior mortgage lender and the mezzanine lender hold claims on the same project, their relationship is governed by an intercreditor agreement that typically runs 40 to 60 pages. This contract is where the power dynamics get fixed in writing.
The most important provisions for the mezzanine lender are cure rights and the purchase option. Cure rights let the mezzanine lender pay off a default on the senior mortgage to prevent a senior foreclosure that would wipe out the mezzanine position. Cure periods are short, typically five business days for missed payments and ten for other defaults, measured from the date the mezzanine lender receives notice. Most agreements cap how long cures can continue, so the mezzanine lender cannot indefinitely prop up a failing borrower by covering senior payments.
If a cure is not viable, the mezzanine lender often has the right to purchase the senior loan at par: full outstanding balance plus accrued interest and fees. Notice usually has to be delivered at least ten days before any foreclosure sale. Buying the senior loan gives the mezzanine lender control of both debt positions and the ability to restructure from the top of the capital stack.
In exchange, the mezzanine lender accepts standstill restrictions. During the standstill period, the mezzanine lender cannot enforce its own remedies against the borrower’s equity without the senior lender’s consent. The senior lender’s view is that it advanced the larger, lower-cost loan and should not have to worry about a junior creditor destabilizing the project.
The Payment Waterfall
Cash flow from the property follows a rigid sequence called the payment waterfall. Monthly borrower payments go into a master servicing account, and the trustee distributes them according to the deal’s governing documents.
Inside the CMBS trust, the AAA tranche is paid first, all scheduled interest and principal due. Once the AAA is current, the AA tranche is paid, then the A, and so on down through the investment-grade and sub-investment-grade classes. Only after every tranche has received its full allocation does remaining cash flow go anywhere else.
Mezzanine lenders sit outside this trust waterfall entirely. They are paid directly by the borrower, not by the trust. Their payment comes after the senior mortgage is current but before the property owner takes any profit. If the property generates $1 million in net operating income and the senior mortgage payment is $700,000, the mezzanine lender gets its monthly debt service out of the remaining $300,000, and the equity holder keeps whatever is left.
Losses climb the waterfall in reverse. The unrated B-piece takes the first dollar. If losses exceed the B-piece balance, they eat into the B-rated tranche, then the BB, and so on upward. This reverse-sequential loss allocation is why the AAA tranche carries the lowest yield: it is the last to lose money, with 25 to 30 percent of the deal’s capital absorbing losses beneath it in a typical conduit CMBS.
What Happens When a CMBS Loan Goes Bad
Day-to-day loan administration is handled by a master servicer. Once a loan is delinquent beyond a specified threshold, typically 60 days, it transfers to a special servicer, a separate firm with workout expertise and broad discretion to resolve the problem.
The special servicer’s options include loan modifications (extending maturity, cutting the interest rate, or restructuring payments), forbearance agreements, negotiated property sales, foreclosure, receivership, deed-in-lieu arrangements, and discounted payoffs. The choice turns on a net-present-value analysis aimed at maximizing recovery for the trust’s bondholders, not keeping the borrower in the deal.
During special servicing, the servicer may stop advancing full interest payments on the troubled loan. If a new appraisal shows the property is worth significantly less than the loan balance, an appraisal reduction is calculated and interest shortfalls are allocated in reverse sequential order starting with the most junior tranche. Those shortfalls can persist for months or years while the workout plays out, eroding returns for subordinate bondholders even if the loan ultimately resolves without a total loss.
The potential for conflicts of interest in special servicing is real and well documented. A special servicer that also owns the B-piece, for example, may be motivated to pursue foreclosure and acquire the property rather than approve a modification that would benefit the senior tranches.
Getting Out Early: Defeasance and Yield Maintenance
CMBS loans almost never allow free prepayment. The bondholders bought a stream of fixed cash flows, and an early payoff would force them to reinvest at whatever rates the market offers that day. To protect those cash flows, CMBS loans lock borrowers in through one of two mechanisms.
Defeasance is a collateral substitution, not a payoff. The borrower buys a portfolio of U.S. Treasury or agency securities engineered to replicate every remaining scheduled payment on the loan, including the balloon at maturity. That portfolio replaces the real estate as collateral for the trust, and the borrower gets the mortgage lien released. The loan itself stays in the trust and keeps paying bondholders as if nothing had changed. Cost depends on Treasury prices at the time: low yields and high prices make defeasance expensive. The borrower also pays legal, accounting, and intermediary fees to put the portfolio together.
Yield maintenance works differently. The borrower pays off the remaining principal balance plus a penalty designed to make the lender whole for lost interest. The penalty is generally the present value of the difference between the loan’s rate and the current Treasury rate for the remaining term, applied to the outstanding balance. A loan at 5.5 percent against a comparable Treasury at 4 percent produces a penalty equal to the present value of that 1.5 percent spread over the remaining payment periods. Penalties typically carry a floor of 1 percent of the loan balance, and less favorable loan terms may set the floor at 3 percent.
Most CMBS loans also include a brief open window, usually the last few months before maturity, when the borrower can prepay without penalty. Outside that window, the lockout is absolute for the first two to five years, after which defeasance or yield maintenance becomes available depending on the loan’s terms. Any borrower planning a refinance or sale before maturity has to know which mechanism applies and when it opens.
Risk Retention and REMIC Treatment, in Brief
Two regulatory frameworks shape every modern CMBS deal. Since December 2016, federal rules have required at least one sponsor to retain a 5 percent economic interest in the credit risk of the securitized loans.3Office of the Law Revision Counsel. 15 USC 78o-11 Credit Risk Retention The sponsor can satisfy that with a vertical slice (5 percent of each tranche), a horizontal slice (a first-loss position worth at least 5 percent of the deal’s fair value), or a combination. Most sponsors use the horizontal option, which is why the B-piece buyer or the sponsor itself ends up holding the most subordinate interest in the trust. To qualify as an eligible horizontal residual interest, the position has to absorb losses and shortfalls before any other class in the deal.4eCFR. 17 CFR Part 246 Credit Risk Retention Federally insured or guaranteed loans, such as FHA-insured multifamily mortgages, and Farm Credit System loans are exempt.
Nearly every CMBS trust is organized as a Real Estate Mortgage Investment Conduit, or REMIC, to avoid double taxation. The trust pays no federal income tax; interest flows through to the bondholders, who are taxed individually.5Office of the Law Revision Counsel. 26 USC 860A Taxation of REMICs REMIC status comes with strict conditions on the kinds of assets the trust can hold and when they can be contributed,6Office of the Law Revision Counsel. 26 USC 860D REMIC Defined and prohibited transactions are taxed at 100 percent of the net income from the transaction.7Office of the Law Revision Counsel. 26 USC 860F Other Rules The practical consequence for anyone dealing with a CMBS loan is that the trust must stay passive. It holds mortgages, collects payments, and passes them through. That is why loan modifications in special servicing are so constrained, and why prepayment has to run through defeasance or yield maintenance rather than a simple payoff.