One morning in February, Matthew Allain, the senior managing director of the Leo Group, a private wealth-management company, visited a town house on Central Park West in order to discuss an unusual acquisition. The town house was the headquarters of Carpenter Fine Violins, a dealer in rare stringed instruments. It was also the home of Sean Avram Carpenter, the company’s thirty-three-year-old C.E.O.; Sean’s sister, Lauren Sarah Carpenter, twenty-nine, who is the company’s C.O.O.; and their brother David Aaron Carpenter, twenty-eight, who serves as C.F.O.

Allain joined the siblings for a breakfast meeting, around a dining-room table laden with bagels, smoked fish, quiche, salads, and cookies. A sentimental painting, by Alfred de Dreux, of a girl flanked by two dogs dominated one wall. Allain explained that the Leo Group had been attempting to formulate a sophisticated tax strategy: “We were looking for a rare, and illiquid, asset.” He had considered buying art, but, after meeting Sean Carpenter, through a colleague, he was persuaded that a violin would be a better solution to his tax puzzle, and represent a solid investment as well. The value of a Stradivari violin has never gone down; for the past forty years, the violins have increased in value at an average annual rate of between eight and twelve per cent. Affluent music lovers who foresaw the potential of investing in instruments have reaped rewards. The Carpenters point to David Fulton, a software entrepreneur who attended the University of Chicago and was the concertmaster of the student orchestra there. Fulton began collecting violins three decades ago and amassed one of the greatest collections in history. In the past decade, he has begun a very profitable process of divestment.

The Carpenters had the very thing for Allain: a Stradivari violin that had just gone on the market. It was lying in its silk-lined case in the parlor down the hall. The seller, Lauren explained, was “in a liquidity crunch.” Lauren, who was a senior account manager at Google until she and her brothers started the business, four years ago, is shrewd and practical. Discretion about the seller’s identity was necessary, she said: “Our family deals a lot with the three D’s—distress, divorce, and, unfortunately, death.” The violin, which dated from Stradivari’s so-called golden period, at the beginning of the eighteenth century, was in good, if not perfect, condition. The price was in the low millions.

The Leo Group had its own unusual requirement: it wished to pay in bitcoin. One of its clients had significant holdings of the virtual currency. Allain and the Carpenters had arranged a deal involving a “bitcoin swap”: a newly created framework would hedge the risk, so that the agreed-upon dollar price would be guaranteed for both seller and buyer, despite fluctuations in the value of bitcoin. The Commodity Futures Trading Commission was due to review the unprecedented transaction that morning, and Allain awaited notification on his phone, which was perched next to his espresso cup.

“I see this as old meets new,” Lauren said.

“The way we look at this violin, from an investment point of view, is that this is a store of value,” Allain said. “We are big investors in gold. That’s a store of value, to the extent that someone is saying it’s worth something, just as we think bitcoin is worth something. This Stradivarius—it’s a finite supply. It’s musical gold.”

“That’s a great way of putting it,” Lauren said.

“If you own a Stradivarius, you become part of history’s most exclusive club,” Sean said. He worked as a hedge-fund analyst at Fortress Investment Group before moving on to fine instruments, by which he has been obsessed since childhood. He is quieter than his sister—earnest and sober, with occasional excursions into goofiness. Sean continued, “These instruments were commissioned for royalty and nobility, and for the finest musicians of the day. The finite quality is really exceptional—much more so than gold. I love the comparison, but if the world’s supply of gold runs out there’s another huge supply sitting under water—it’s just expensive to take it out. With Strads, there’s one discovered every fifty years, if that.”

“Maybe we could mine Strads,” David Carpenter offered, lightly. David has the humorous, attention-seeking demeanor of a youngest child. Like his siblings, he is good-looking; tall and slender, he has dark eyes and floppy dark hair that demands to be tossed back from his brow. All three Carpenter siblings are musicians. Sean and Lauren are accomplished violinists, while David, a professional violist, made his solo début in the main auditorium at Carnegie Hall last year, performing with the National Symphony Orchestra.

Allain’s phone vibrated: the commission had approved the deal. Everyone moved to the parlor, which was appointed with French and Italian antiques, gilded mirrors, and a small de Kooning. Sean picked up the violin and tilted it under the window to highlight its visual signatures—the wavy lines created by the grain of the wood, the amber varnish—then played Fritz Kreisler’s “Liebesleid.” The sound that poured forth was brilliant and defined; hearing it in a confined space was almost painful. Then he and the others posed for photographs, Allain proudly holding the instrument. “It’s not often that you find an asset that you may have little knowledge about but everyone knows what it is,” Allain said. “Every single client knew what a Stradivarius was.”

It took another month for the deal to close, and even after it did the violin remained with the Carpenters, who offer to store clients’ instruments in high-security vaults. But the Strad would not languish there. The Carpenters run a not-for-profit chamber orchestra, Salomé, which usually performs for charities, and specializes in accessible classical music—Vivaldi and Brahms. At the town house, Sean explained to Allain that the Leo Group could lend its violin to a Salomé player, as several other clients do. The ensemble is called Salomé because it performs without a conductor—though it might more fittingly be named Cerberus, so dominated are its performances by the Carpenter siblings, with Sean and Lauren flanking David, who holds center stage with dramatic expressions of visage.

David told Allain, “There is a certain act of patronage that goes back to the Medici, when they were commissioning instruments directly from Stradivari. They would have house concerts in their palaces in Spain, or Florence, and they would invite guests over, and they would have famous players of the time play these instruments. In a way, it hasn’t changed since the eighteenth century. It is the same principle, whether it is David Fulton in Seattle or the Medici in Florence—”

“—or the Leo Group,” Lauren chimed in. She offered to arrange a private performance for the company, showcasing the newly acquired instrument and benefitting a cause of the Leo Group’s choosing. Allain looked delighted. “You can’t do that with gold,” he said. “You certainly can’t do that with bitcoin.”

The Carpenters have an air of fictional implausibility, as if they had been imagined into being by Wes Anderson. Siblings often go into business together; they do not often do so while living together well into adulthood. Among friends who have known them since Princeton—which all three Carpenters attended, on financial aid—the ostentatious elegance of their modus vivendi is a subject of fascination.