Michael Bambang Hartono, an Indonesian billionaire who with his younger brother ran one of the country's biggest conglomerates, Djarum group, died on Thursday at the age of 86.

"It is with deep sorrow, Djarum family announces the passing of one of our company’s leaders, Michael Bambang Hartono," Djarum said in a statement posted on its Instagram. "We express our gratitude for his dedication and service."

The cause of death was not immediately clear.

Alongside his brother Robert Budi Hartono, Michael Hartono was worth an estimated $43.8 billion, according to Forbes in 2025, putting them on top of Indonesia's rich list.

The Chinese-Indonesian family is famously media-shy and has disclosed little about their personal lives or their vast holdings.

The brothers took over Djarum, a major clove cigarette manufacturer in the world's No. 2 tobacco market, after their father's death in 1963.

They have since expanded into a range of sectors including electronics, food and beverages, palm plantations, telecommunication towers and technology, with many of those business now run by younger family member.

Djarum also took over Italy's Como football club in 2019.

Much of the family's wealth derives from its 54.9% majority stake in Bank Central Asia BBCA.JK, Indonesia's biggest bank with a market capitalisation of more than $50 billion.

They invested in the lender and a range of other assets in the wake of the 1998 Asian financial crisis and the fall of former Indonesian President Suharto.

In 2018, Michael Bambang became one of the oldest bridge competitors at the Jakarta-hosted Asian Games, winning a bronze medal.

The tycoon, who has been playing the game since the age of six, told Reuters the requirements for bridge were not so different from his day job.

"The decision making process is the same in bridge and business. You gather information and data, make a conclusion, and plan a strategy," he said.

($1 = 16,975.0000 rupiah)

-Gayatri Suroyo/Reuters