Finding out who is actually behind a massive real estate portfolio is usually harder than it looks. For years, the name Mendel Steiner—often called "Mendy" by those who knew him in the Boro Park community—was a quiet but constant presence in the Commercial Real Estate (CRE) world. You’ve probably seen the headlines about 3,000 units across ten cities. Or maybe you saw the $5.3 million deal in Brooklyn last year. But recently, the story of Mendel Steiner real estate took a turn that left the industry reeling.
It's not just about buildings. It’s about a complex web of LLCs, massive debt burdens, and a tragic end that has left bondholders and local communities asking a lot of questions. Honestly, the scale of what he built was pretty incredible for someone who was only 33. But as we're seeing now, the foundation might have been shakier than the public records suggested.
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The Rapid Rise of the Steiner Empire
Mendel Steiner wasn't just another landlord. He was a "macher"—a Yiddish term for a big-time mover and shaker. Based in Brooklyn, he operated largely through a company called Aven Realty, though he was notorious for using a variety of holding companies and even an alias, "Andreas," to conduct business. This isn't exactly rare in New York real estate, but the sheer volume of his acquisitions was staggering.
His strategy? Multifamily. He went deep into the "bread and butter" of the housing market.
Take a look at his 2024 activity. In September, he closed on a 34-unit walkup at 1801 50th Street in Borough Park for $5.3 million. That works out to roughly $155,000 per unit. For Brooklyn, that’s a significant play. But he wasn't just local. He had major holdings in Hollywood, Florida, and Baltimore. In Florida alone, he was dropping nearly $7 million on multifamily complexes like the one at 1610 N Dixie Highway.
Why the Banks Are Nervous
While the portfolio looked impressive on paper, the underlying debt was a different story. According to reports from JPMorgan’s CMBS research desk, Steiner-sponsored loans were flagged as "seriously delinquent" shortly after his death in early 2025. We’re talking about over $214 million in 2023-vintage loans that went sour.
What’s weird is that the properties actually had decent cash flow. They were bringing in money. So why the delinquency?
JPMorgan analysts pointed out that the loans went bad almost immediately after they were originated. This has led to a lot of finger-pointing at the underwriting process. When a loan fails that fast, it usually means the "sponsorship"—the person behind the curtain—wasn't as stable as the banks thought. Investors are now picking through the remains of his deals, trying to figure out how many more loans are hidden under anonymous LLCs.
The Mark Nussbaum Connection
You can’t talk about Mendel Steiner real estate without talking about the legal side. For a long time, Steiner was closely tied to CRE attorney Mark Nussbaum. Since Steiner’s passing, Nussbaum has faced a mountain of litigation. His law firm even shuttered amid the chaos.
There’s an explosive lawsuit in Rockland County that names Nussbaum as a defendant, and much of it stems back to the deals he facilitated for Steiner. It’s a mess of unpaid debts and shell-shocked lenders who thought they were backing a stable, growing portfolio.
Breaking Down the Portfolio
- Aven Realty: The primary vehicle, reportedly managing over 3,300 units.
- Borough Park Holdings: Centered around 1801 50th Street and other local Brooklyn assets.
- Florida Acquisitions: High-PPSF (Price Per Square Foot) deals in Hollywood and the surrounding areas.
- The Debt: At least $140 million in identified delinquent CMBS loans, with more likely hidden.
The Human Element and the Community Impact
Beyond the numbers, Steiner was a well-known figure in the Orthodox Jewish community. He was the son of R' Yakov Shia Steiner and a son-in-law to R' Duvid Endzweig. He was known for philanthropy, supporting various "mosdos" and "kehillos" (institutions and communities). When news of his death spread through WhatsApp groups in January 2025, it wasn't just a business story; it was a communal tragedy.
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There were reports that he had been "unwell" in recent years, but the suddenness of his passing—reported as a suicide—left a void that immediately filled with legal and financial panic. It’s a reminder that even the most aggressive real estate empires are often tied to the health and stability of a single individual.
Actionable Insights for Investors and Observers
If you’re looking at the fallout of the Steiner portfolio, there are a few things you can actually do to protect yourself or understand the market better:
1. Audit the Sponsorship, Not Just the Property
The Steiner case proves that a property can have a 9.9% debt yield and still fail if the sponsor is overleveraged elsewhere. If you're investing in syndications, ask for a "schedule of real estate owned" (SREO) from the lead developer. You need to see their total debt across all entities, not just the one you're funding.
2. Watch the CMBS Delinquency Reports
If you want to track where the next "Steiner-level" collapse might happen, keep an eye on JPMorgan or Trepp’s monthly CMBS delinquency data. Specifically, look for 2023 and 2024 vintage loans. These were originated in a high-interest-rate environment, and any early delinquency is a massive red flag.
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3. Be Wary of Multi-LLC Structures
While LLCs provide protection, a "macher" using ten different names for ten different buildings is often hiding a cross-collateralization nightmare. Use tools like "Who Owns What" or local ACRIS records to see if a single person is accumulating too much debt in a concentrated area.
The story of Mendel Steiner real estate is still being written in the courts. It serves as a cautionary tale of how fast a multi-city empire can crumble when the person at the center is no longer there to hold the house of cards together. For now, the focus remains on the creditors trying to claw back whatever value is left in those 3,000 units.