David Koch, the co-owner of major tanker and bulker charterer Koch Industries, has died at the age of 79.
Together with elder brother Charles, Koch was the world's eleventh richest person.
His death was reported by the New Yorker.
Koch Industries is reportedly the second-largest private US company.
Koch served as the VP of the multinational corporation until 2018, announcing his retirement last year as his health deteriorated.
Charles Koch, the chairman and CEO of Koch Industries, said in a statement: “It is with a heavy heart that I announce the passing of my brother David.
“Anyone who worked with David surely experienced his giant personality and passion for life. Twenty-seven years ago, David was diagnosed with advanced prostate cancer and given a grim prognosis of a few years to live.
“David liked to say that a combination of brilliant doctors, state-of-the-art medications and his own stubbornness kept the cancer at bay. We can all be grateful that it did, because he was able to touch so many more lives as a result.”
The brothers pumped millions of dollars into the US political system, promoting a conservative agenda,.
David Koch had a personal fortune of $42.4bn (£34.6bn) through his stake in Koch Industries.
Last month, it sealed a series of charters for bulkers with Tor Olav Troim-backed 2020 Bulkers.
2020 said the contracts involved subsidiary Koch Supply & Trading.
