BRIDGEWATER, CONN. — Investment banker turned Modern and Postwar art dealer Robert Mnuchin died Friday, December 19; his death was confirmed by Michael McGinnis, a partner at Mnuchin Gallery in New York City.

Mnuchin was a major force at the top tier of the art market, exhibiting works by Willem de Kooning, Andy Warhol, Mark Rothko and Franz Kline. He was also known as an advisor to billionaires like Steve A. Cohen and Mitchell Rales.

Born in 1933 in Manhattan, Mnuchin grew up in a Jewish family in Scarsdale, N.Y., and his parents collected Modern art on a modest scale. After graduating from Yale University in 1955, he served in the US Army. In 1957, he joined Goldman Sachs, where he built a successful career over 33 years, retiring in 1990 to pursue his passion for art.

Mnuchin opened his first gallery, C&M Arts, by partnering with Los Angeles dealer James Corcoran in 1992. It specialized in Abstract Expressionism. In 2005, he joined forces with Dominique Lévy, changing the gallery’s name to L&M Arts. The two remained partners until 2013, when Lévy struck out on her own. From then on, the business was known as Mnuchin Gallery.

One of Mnuchin’s early clients was Rales, who was then starting on his collecting journey. Mnuchin helped him acquire major works by De Kooning, Rothko and Twombly, often for record prices. These works are now part of Rales’s private Glenstone museum in Potomac, Md., just outside Washington, DC.

In 2019, Mnuchin won Jeff Koons’s sculpture “Rabbit” (1986) on behalf of Cohen at Christie’s for $91 million, the auction record for a living artist. The news was all the more remarkable since one of Mnuchin’s sons, Steven, was the US Treasury secretary at the time.

In recent years, Mnuchin expanded his gallery’s focus to include more women artists and artists of color, with shows devoted to Lynne Drexler, Sam Gilliam and Ed Clark.

Mnuchin remained involved with the gallery up to the end.