Sam Altman Paid $27M for San Francisco's Most Expensive Home. Then the Infinity Pool Flooded His Basement with Sewage.

The OpenAI CEO bought Russian Hill's crown jewel in 2020, sued the developer four years later after the infinity pool drowned the lower level, and then bought the entire block anyway.

Landlord Ledger Publications • Profile • 2026-05-30

In March 2020, Sam Altman paid $27 million for 950 Lombard Street, then the most expensive residential listing in San Francisco: a 9,500-square-foot Russian Hill compound with a cantilevered infinity pool, a Batcave garage, a wellness cottage, and sweeping views of the bay. Four years later, his lawyers filed suit in San Francisco Superior Court, calling it exactly what it was: a $27 million lemon. The infinity pool had flooded the entire subfloor of the lower level. A disconnected sewer pipe had dumped raw sewage on the side of the property. Repairs were estimated at over $4 million. Then, in early 2025, Altman turned around and bought the three adjacent properties on the same block for $38.5 million, because apparently even a sewage catastrophe does not dull a billionaire's neighborhood ambitions.

The Crown Jewel of Russian Hill

The property at 950 Lombard Street had every credential a trophy buyer could want. Designed in 1907 by Willis Polk, one of San Francisco's most celebrated architects and the man behind the city's pioneering Hallidie Building on Sutter Street, the original shingled mansion was extensively rebuilt by Greg Malin and his firm Troon Pacific into a 9,500-square-foot modern compound that sprawled across two hillside lots. The asking price when it hit the market in 2018 was $45 million, making it the most expensive residential listing in the city.

The amenities were a catalogue of tech-era excess: a cantilevered infinity-edge pool suspended over views of San Francisco Bay, a two-story subterranean art gallery with humidity controls, a glass elevator to all levels, marble-encased master bathrooms, an 850-square-foot wellness cottage, century-old olive trees in a gated garden, and a concrete tunnel entrance leading to a four-car garage with a turntable floor for rotating vehicles. Malin described the garage in Architectural Digest as a "Batcave." The home was "extraordinarily unique" with "world-class amenities," he told the magazine.

In March 2020, after the listing had sat for two years and the price had been cut by $18 million, an LLC tied to Sam Altman bought it. Altman was then a prominent venture capitalist who had invested in Stripe, Reddit, and Airbnb; within months, he would become one of the most consequential figures in the history of technology. The property became his primary San Francisco address, the registered business home of Apollo Projects, the early-stage investment firm he runs with his brother Jack Altman.

What the Pool Was Actually Doing

Not everything about the property could be seen on a video tour. The lawsuit filed in San Francisco Superior Court in July 2024, on behalf of 950 Lombard LLC against Troon Pacific and Eight Forty One LLC, alleged that beneath the polished surfaces lay systemic construction failure.

The centerpiece defect was the infinity pool itself. According to the complaint, viewed by Fortune, the pool suffered from "poor and substandard waterproofing design and installation." The consequences were not merely cosmetic: chlorinated water seeped out of the 40-foot pool, filled the entire subfloor of the lower level of the home, and then poured down through the ceiling of the at-home gym below. Estimates to remediate the hazardous condition, replace the pool, and repair the damage exceeded $4 million. The complaint reached for a single phrase to summarize the situation: the owner had been misled into buying a "$27,000,000 lemon."

The pool was only the headliner. The complaint alleged that improperly installed sewage lines discharged raw sewage directly onto the side of the property. A separate sewer blockage, the lawsuit alleged, was caused by an unpaid subcontractor who had stuffed bags into the pipes, apparently in retaliation for not being paid. Water leaked through improperly installed skylights. Irrigation pumps throughout the garden failed. The complaint stated that Troon Pacific had been "aware of pervasive and significant defects" related to the pool system, plumbing, sewer systems, waterproofing, and drainage, and had misrepresented the property's condition to close the sale. The lawsuit sought unspecified damages plus interest and attorneys' fees.

The Developer Behind the Dream

The lawsuit against Greg Malin landed in a courthouse that had already developed a working familiarity with him.

Malin arrived in San Francisco from Los Angeles in 1989, worked as a property receiver managing distressed assets, and eventually co-founded Troon Pacific with his wife Charlot as a family business centered on high-design, sustainable luxury homes. After a successful 2010 project in which Troon bought a Pacific Heights house for $6 million and sold it for $13.5 million after converting it to LEED Platinum certification, the firm began marketing "healthy living" as its core differentiator: clean air, wellness built into the architecture, sustainability as amenity. A 2018 feature in Haute Living described Malin as a generous visionary. A judge's ruling would eventually describe him differently.

The Lombard Street project was different in scale and execution. Troon had bought the Russian Hill property in 2012 for $4.5 million and began an extensive rebuild. In 2017, the city accused the company of demolishing parts of the historic Polk-designed house without a permit; Troon paid a $400,000 settlement without admitting wrongdoing. The build continued, the asking price climbed to $45 million, and the Architectural Digest feature went live.

Meanwhile, Malin had raised money from outside investors to fund a portfolio of five luxury spec homes across San Francisco. By the time Altman's lawsuit was filed in July 2024, a California arbitrator had already ordered Malin and Troon Pacific to pay more than $50 million in damages and legal fees to investors who alleged the developer had squandered $35 million through self-dealing, fraud, and embezzlement. A San Francisco Superior Court judge, upholding that ruling the same week Altman's complaint was filed, found that Malin and Troon had breached their fiduciary responsibilities. Malin denied wrongdoing, attributing losses to COVID and market conditions.

The post-judgment picture grew stranger. By March 2025, court documents showed Malin claiming to be broke while ten months of credit card records, as reported by the San Francisco Chronicle, showed spending that included $3,000 at a cigar shop, $3,000 at Zuni Cafe, $3,700 in club nights at the Battery, two trips to Europe, three trips to Cabo, and $13,056 for a pair of Aer Lingus tickets to Ireland. Attorneys for the defrauded investors alleged in court filings that Malin had transferred his $15 million home, two cars, and an art collection into an irrevocable trust in his sons' names to shield them from creditors.

A Man Who Buys the Block

What makes the Altman story genuinely strange is what came next.

In late January 2025, through Amberley Properties LLC, an entity managed by his cousin Jennifer Serralta, the COO of his family office, Altman purchased the three adjacent properties on the same Russian Hill block: a 5,400-square-foot five-bedroom home built in 1924 at 855 Chestnut Street, previously owned by Stanford professor Thomas Rohlen, and two adjoining vacant lots at 952 and 954 Lombard. Public records listed the combined purchase at $14 million; the San Francisco Association of Realtors MLS recorded the transaction at $38.5 million, each address at $12.833 million.

Together with the original $27 million purchase, Altman now controls over $65 million worth of property on a single Russian Hill block, creating what amounts to a private compound steps from the city's most photographed tourist attraction. The addition of the vacant lots pushes the footprint away from Lombard Street's crooked section, offering unusual privacy in one of San Francisco's most densely visited neighborhoods. He is not the first tech billionaire to consolidate a neighborhood footprint: Mark Zuckerberg bought his Mission District home in 2012 and sold it for $31 million in 2022 before turning his attention to Lake Tahoe and Kauai. But Altman is doing it while suing the original developer, and while the case is designated complex litigation with hearings still scheduled into 2026.

What the Walls Couldn't Show

There is a line from the Architectural Digest video tour that deserves to be considered carefully. Malin, speaking about the craftsmanship of the Lombard Street project, told the interviewer: "A lot of what we do you can't see."

He was talking about quality. The pipes, the waterproofing membranes, the structural work behind the walls. The invisible infrastructure that separates a properly built house from one that eventually turns against its owner. Malin's point, delivered to Architectural Digest's audience of wealthy homebuyers and design enthusiasts, was that Troon's real value lay in workmanship that no glossy tour could capture.

Four years later, Sam Altman's lawyers discovered exactly what was behind those walls.

The case is a pointed illustration of something the luxury real estate market tends to obscure: the gap between presentation and construction is widest at the top of the market, where the finishes are spectacular enough to distract from the fundamentals. A $27 million price tag buys exceptional stone and custom millwork and a cantilevered pool with underwater speakers and a turntable garage for cars emerging from a concrete cave. It does not, by itself, buy a sewer pipe that is connected to anything, or waterproofing that waterproofs.

As of this writing, the lawsuit is active, the case management conference is on the calendar, and Malin's financial reckoning with his investors continues in parallel. Sam Altman, whose company is building systems intended to reshape civilization, continues expanding his Russian Hill compound one block at a time, apparently undeterred by the discovery that the most expensive home in San Francisco came with a sewer problem and a Batcave that floods.