Founder's Note
A bond rated AAA is about to lose money on an office building. Centre Square, two towers on Market Street in Philadelphia, was appraised at $471 million in 2019 and backs a $368 million commercial mortgage bond. A judge has approved its sale for $70 million, 85% below that appraisal. The seven lower slices of the bond are expected to be wiped out, and the top slice, sold as the safest paper in the deal, is expected to recover only about 44 cents on the dollar.
Centre Square was 93% leased in 2020, the year it was refinanced into that bond, and 28% leased this June. Nothing in the bond's design could fix that. Seniority, subordination and credit ratings all do one job: they set the order in which investors absorb a loss. None of them has any say over how large the loss turns out to be. That is decided by the building, by who pays rent in it, and above all by the price someone paid for it.
My read: the first number I look for in a deal is not the target return, it is the basis. What was paid, against what comparable buildings actually sell for, and how much debt sits in front of the equity. A low basis is the one protection that works at every level of the stack.
This Week in Markets
1. The office bust has moved from empty floors to realized losses
Chicago's Aon Center, bought for $712 million in 2015, was appraised at $195 million in May against $536 million of mortgage-bond debt. The loan matured in July, and the special servicer "unequivocally denied" the owner's request for a three-year extension. Nationally, about $64 billion of office loans held in commercial mortgage bonds come due this year and next, and nearly $40 billion of that is already delinquent, in default or on a watchlist, according to Bloomberg. Trepp puts the office delinquency rate near 12%.
Why it matters: An extension is how a loan buys a building time to recover. Once servicers stop granting them, a loss on paper becomes a sale price, and Deutsche Bank finds distressed office sales closing about 20% below even recent appraisals.
2. Pimco held the top of the Centre Square bond, and the loss reached it anyway
Pimco is the largest holder of the bond behind Philadelphia's Centre Square, with about $58 million of face value, roughly half of it in the top-rated slice. Bloomberg estimates its losses will exceed $35 million. The towers were bought in 2017 for $328 million and refinanced in 2020, weeks before Covid. The new owners plan a 300-room hotel and up to 500 apartments. Bank of America's Alan Todd expects more: "Over the next year or two, more of these loans will come due."
Why it matters: A bond secured by one building is a bet on that building, however finely it is sliced. Diversification lives in the collateral, not in the tranche. When you are offered a senior or preferred position, ask what sits underneath it first.
3. The other half of office: AI tenants are signing long, direct leases
AI companies leased 2.9 million square feet in San Francisco in the first half of 2026, more than in any prior full year, and 1.7 million in Manhattan, more than 2024 and 2025 combined, according to Savills and CompStak. They have moved out of discounted sublets and into direct Class A space. The average AI lease in Manhattan now runs 90.9 months, up from 49 in 2020, and starting rents there rose 9.1% to $93.85 a foot. Availability in San Francisco's Mission Bay fell from 36.8% to 17.6% since late 2023.
Why it matters: The asset class wiping out bondholders in Chicago and Philadelphia is tightening in two other cities. The word "office" tells you almost nothing. The building, the block and the tenant roster tell you almost everything.
The Take
Every capital stack is a queue of people waiting to be paid out of the same building. The senior lender stands at the front, any mezzanine lender behind, and the equity, which is usually you, at the back. When the building does well, the back of the queue keeps the upside. When it does badly, the back of the queue goes home first. This week, for only the third time since 2008 by Bloomberg's count, the loss walked the full length of the queue and reached a AAA bond at the front.
So what actually protects the investor at the back? Not the structure. Structure is fixed the day the deal is signed, and it only ever answers one question, whose money goes first. The real protection is a gap: the distance between what the building is worth and what is owed on it. That gap is widest on the day of purchase if the buyer paid well, and it is the only thing that gives an equity investor room to be wrong about rents, rates and timing. Three questions find it before you commit.
One. Ask what was paid, and against what. A price per unit or per foot means nothing on its own. Set it against what similar buildings nearby have actually sold for, and against what it would cost to build today. Buying below both creates a cushion no tranche can manufacture.
Two. Ask how much debt stands in front of you, and when it comes due. Aon Center's owner asked for three more years and was told no. A maturity date is the day a building's value stops being an opinion. Fixed-rate debt with a term that runs past the business plan moves that day beyond the planned sale instead of into the middle of it.
Three. Ask who pays the rent, and why they will keep paying it. No basis survives a building going from nearly full to under a third leased. In Manhattan, AI firms are signing leases of seven and a half years in the same asset class. The tenant roster is what holds a price up after you have paid it.
But the principle outlasts any one deal. Ratings, seniority and preferred returns decide who absorbs a loss first. Only the purchase price and the tenants decide how big that loss gets. A AAA bond on Market Street is learning it this week, at an expected 44 cents on the dollar. Target returns remain targets, a low basis can still lose money, and past performance does not predict future results. Before you ask where you sit in the stack, ask what the building cost.