Real estate in Brooklyn isn't just about brownstones and artisanal coffee shops. It's a high-stakes, often opaque world where names you've never heard of control thousands of units across the country. One of those names that recently sent shockwaves through the Borough Park community and the wider commercial real estate (CRE) industry is Mendy Steiner.
If you were looking for him on a flashy "top 40 under 40" list, you probably wouldn't find him. He operated in the shadows, a classic Brooklyn "macher"—a Yiddish term for a big-time operator or dealmaker. But when the news broke in early 2025 about his sudden passing at the age of 33, it wasn't just a community mourning a young father and philanthropist. It was the start of a massive financial unraveling.
Who Was the Real Mendy Steiner?
Mendy Steiner—officially Mendel Steiner—was a key figure in the Brooklyn multifamily scene. He lived and worked in the heart of the Orthodox Jewish community, specifically in Borough Park. While many locals knew him for his generosity to mosdos (educational institutions) and local charities, the business world knew him as an aggressive, fast-moving investor.
Basically, he was a massive multifamily dealmaker. At the peak of his activity, he reportedly controlled over 3,000 units nationally. You might see his name tied to properties in Brooklyn, but his reach went way further—Baltimore, Hollywood, Florida, and beyond. He often used various holding companies or even aliases like "Andreas" to move under the radar.
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One of his main vehicles was Aven Realty. According to industry data, Aven controlled nearly 3,300 units across 10 different cities. That's a huge operation for someone who kept such a low profile.
The CMBS Meltdown and the $214 Million Problem
Here is where things get messy. In late 2024 and early 2025, the commercial mortgage-backed securities (CMBS) market started flashing red. JPMorgan’s research desk pointed out that a significant chunk of "delinquent" loans from the 2023 vintage were sponsored by Steiner.
We are talking about $214 million in loans that went sour almost immediately after they were signed.
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The weird part? The properties were actually making money. They had enough cash flow to cover the debts. So why weren't the bills being paid? It’s the kind of mystery that makes bondholders lose sleep. Industry insiders have speculated that Steiner was caught in a "last-ditch attempt" to get a portfolio-wide refinance to pay off private creditors in Brooklyn and Lakewood, New Jersey. When that deal didn't happen, the house of cards started to wobble.
The Legal Chaos Left Behind
When a major player like Mendy Steiner passes away under such tragic circumstances—he reportedly took his own life in January 2025—the legal battles don't stop; they just change targets.
- Mark Nussbaum: Steiner’s longtime associate and real estate attorney has been at the center of the storm. Following Steiner's death, Nussbaum shuttered his law firm and faced multiple lawsuits, including allegations of fraudulent transfers related to Florida deals.
- Blueberry Funding: There was a massive lawsuit involving a $60 million judgment against Steiner.
- The "Frum" Community Impact: In places like Borough Park, business is often done on handshakes and personal trust. When a "macher" falls, it impacts local lenders and private investors who may not have the same protections as big banks.
Why This Matters for Brooklyn Real Estate
The story of Mendy Steiner is a cautionary tale about the current state of the CRE market. It's not just about one man. It's about the extreme pressure of high-interest rates, the complexity of LLC ownership, and the "bad-boy" carveouts in loan contracts that can ruin a reputation overnight.
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Honestly, it's a lot to process. On one hand, you have a man who was a respected philanthropist, a son of R’ Yakov Shia Steiner, and a pillar of his community. On the other, you have a mountain of debt and a trail of shell companies that have left the CMBS market scratching its head.
Actionable Insights and Next Steps
If you are an investor or someone following the Brooklyn real estate market, here is what you need to take away from the Mendy Steiner situation:
- Verify Sponsorship: If you are investing in syndications or debt, look past the LLC name. Find out who the actual "warm body" guarantor is. The Steiner case showed that even cash-flowing properties can fail if the sponsor is overleveraged elsewhere.
- Watch the CMBS 2023 Vintage: Many loans originated in 2023 are facing "stress tests" right now. Keep an eye on delinquency reports from firms like JPMorgan or Trepp to see if other "silent" portfolios are starting to crack.
- Understand the "Macher" Economy: In tight-knit communities like Brooklyn or Lakewood, private lending often bypasses traditional banks. This creates a hidden layer of debt that isn't always visible until a crisis hits.
- Legal Protections: If you are a creditor, ensure your "confession of judgment" filings and personal guarantees are ironclad. The lawsuits following Steiner's death show how difficult it is to claw back funds once assets are tied up in complex estate litigation.
The real estate landscape in Brooklyn is changing. The days of flying under the radar with thousands of units and millions in debt are getting harder as transparency becomes the new standard for lenders.