Meet Julia Flesher Koch, The Billionaire Philanthropist Who's One Of The World's Richest Women

At the time of his death, David Koch was worth $42.5 billion, according to a Forbes estimate, making him one of the richest people in the world.

They were married for 23 years.

Forbes pegged Flesher Koch's net worth at $84.6 billion as of October 7, 2026. This makes her the third richest woman in the world, after Alice Walton and Françoise Bettencourt Meyers.

Alongside her children, Flesher Koch inherited a 42% stake in Koch, Inc. after her husband's death in 2019.

In the early 1990s, she was photographed at high-profile events, including the opening of the Metropolitan Museum of Art's Costume Institute Exhibition.

She worked as an assistant to Adolfo, a fashion designer.

However, they didn't hit it off immediately, according to The New York Times.

"Afterward, we shook hands, and I said, 'I'm glad I met that man because now I know I never want to go out with him,''' Flesher Koch told the Times in 1998.

Six months later, they met again and started dating.

After their marriage, Flesher Koch became a fixture on the New York social scene, according to a 1998 profile in The New York Times.

"Julia's one of those people who occur in New York every few years," fashion editor Patrick McCarthy told the Times in 1998. "She's beautiful, she loves fashion, she knows how to entertain, she's married to an extraordinarily rich man."

Mary Julia Koch works as an associate editor of Free Expression, a daily opinion newsletter by The Wall Street Journal.

David Jr. Koch is the special assistant to the general manager of the Brooklyn Nets, according to his LinkedIn page.

John Koch, the youngest of the three siblings, keeps a lower public profile. BSE Global described him as high-school-aged when it announced the family's investment in 2024.

Business Insider estimated in 2019 that David Koch's known real-estate holdings were worth at least $143 million, based on purchase prices and then-current property estimates.

For years, they lived in a Fifth Avenue apartment once owned by former first lady Jacqueline Kennedy Onassis that Koch bought in 1995 for $9.5 million, according to The New York Times.

Koch paid about $18 million for the duplex at 740 Park Avenue in 2004, according to The Real Deal.

740 Park Avenue is notoriously exclusive and expensive. To live in the Art Deco co-op, which opened in the 1930s, Business Insider reported in 2017 that at the time prospective buyers reportedly needed at least $100 million in liquid assets.

Flesher Koch sold the duplex in 2025 for $45 million, The Wall Street Journal reported, citing property records.

Sources told the New York Post in August 2018 that Koch and Flesher Koch paid cash for the property.

The eight-bedroom Upper East Side home, which was originally listed for $51 million, included a 1,500-square-foot primary suite, a gym, and a rooftop terrace.

The Wall Street Journal reported that Flesher Koch sold the property for $41 million in an off-market deal in 2023.

In 2022, Flesher Koch bought two apartments at 4 East 66th Street from the estate of Microsoft cofounder Paul Allen for a combined $101 million, The Real Deal reported.

At the time, The Real Deal reported that this was the most expensive co-op sale in New York's history.

One is the longtime mansion she has owned since the 1990s; in 2021, she bought the adjoining oceanfront estate for $70 million, The Wall Street Journal reported.

In 2025, she expanded her holdings again, paying $33.5 million for a property on the bayfront, according to property records cited by the Journal.

David Koch bought two neighboring Aspen properties in 1989 and 1991 for $1.9 million and $1.75 million, respectively, according to Pitkin County property records previously reviewed by Business Insider.

Julia Koch still has a residence in Palm Beach. The Wall Street Journal reported in 2026 that she was the wealthiest property owner in the town.

Through the David H. Koch Charitable Foundation and personal giving, the couple had donated more than $1.3 billion, according to the Julia Koch Family Foundation website.

Flesher Koch remains president of the David H. Koch Foundation, according to its latest tax filing for 2024.

Flesher Koch has also donated to NYU and NYU Langone Health. She gave $3 million to establish an endowed professorship in orthopedic surgery and $1.4 million to create an endowed scholarship that covers the full tuition of at least one medical student at a time.

Julia Koch is the founder and chair of the foundation. The foundation has committed $75 million to an NYU Langone ambulatory-care center in West Palm Beach, pledged $50 million to The Metropolitan Museum of Art, and made grants to several Brooklyn nonprofits."

BSE Global owns the Brooklyn Nets, New York Liberty, and the Barclays Center.

Forbes reported that the deal was worth almost $700 million.

The deal valued the team at over $10 billion, according to Forbes.

"My family and I are honored to join the Giants organization, a storied franchise with deep roots in New York," Julia Flesher Koch said in a New York Giants press release announcing the deal.