Mustafa Koç, a Turkish billionaire and alumnus, died from a heart attack at the age of 55 Thursday.

Koç, the former chairman of the board of Koç Holding, graduated from the GW School of Business’s master’s program in 1984. University President Steven Knapp traveled to Turkey in November 2014 to meet with Koç and start an exchange program at Koç University, an institution started by Koç’s grandfather.

The program allows students to study at the university in Istanbul for up to one year, which Knapp said at the time will strengthen GW’s ties to its about 200 Turkish alumni.

As chairman of Koç Holding for 13 years, Koç led a conglomerate made up of manufacturing, energy, automotive and finance companies. He maintained strong relationships with businesses like Fiat SpA and Ford Motor Company, according to Bloomberg Business.

He was worth about $1 billion at the time of his death, according to Forbes.

Knapp said in a statement that GW has lost “a great friend” and a “very distinguished alumnus” with the loss of Koç.

“The admiration of his fellow alumni was palpable, and he spoke with warmth and enthusiasm about his love of GW,” Knapp said.

Koç was born in Istanbul in 1960 and was one of three brothers. He went to Lyceum Alpinum Zuoz, an international school in Switzerland for his undergraduate degree before attending GW’s business school. He leaves behind his wife, Caroline, and two daughters, according to The New York Times.

Linda Livingstone, the dean of the business school, said Koç was the first business school alumnus to be a Robert P. Maxon lecturer, a lecture series for leaders in global management.

She said Koç was a “pioneer for economic and social development in Turkey.”

“His loss will be felt not only by family and friends, but by those also seeking a sustainable and equitable world,” Livingstone said.

Derin Dayigil, a member of the GW Turkish Alumni Association, said Koç was well known for his philanthropy and support of museums, arts and culture. Koç was affiliated with businesses and nonprofits like the Education Volunteers Foundation, the World Monuments Fund and the United Nations’ He For She campaign to promote gender equality.

“A kindhearted and down-to-earth titan who made you feel like you knew him your entire life,” Dayigil said. “His energy and optimism lit up every room he walked into.”