NEW YORK — Daniel K. Ludwig, the son of a cargo ship captain who became one of the world's richest men, has died at the age of 95, it was announced Friday.
Ludwig, who owned about 60 oceangoing vessels at the height of his shipping career, died Thursday at home in Manhattan, according to R. Palmer Baker Jr., executor of Ludwig's estate.
Ludwig had been ill for some time and had not been active for five years, Baker said.
In addition to his shipping interests, Ludwig's National Bulk Carriers Inc. invested in forest products, oil and gas, coal and other minerals, hotels and real estate and ranching and agriculture. The conglomerate had operations in 23 countries.
In his later years, Ludwig devoted much of his attention to the Ludwig Institute for Cancer Research, which he founded in 1971. The institute has a staff of more than 500 scientists and technicians working in 10 offices in seven nations.
Forbes magazine estimated Ludwig's fortune at $1.2 billion last October. However, the magazine does not list him as one of the world's billionaires in its current issue.
Of his ability to sense a profit-making opportunity, Ludwig once said: "Nearly everyone has these antennae. Most people just don't use them."
Born in South Haven, Mich., Ludwig quit school at 19 and entered the shipping business by borrowing $5,000 to convert an old steamer. By the 1930s, he would charter ships even before they were built, and then use the charters as collateral for loans to build the ships.
His companies built tankers for the government during World War II and got them back free after the war's end. He also built the world's first supertankers in Japanese shipyards.
In the 1960s and '70s, Ludwig lost a reported $1 billion in an ambitious plan to produce wood pulp and rice on the Amazon's Jari River.
Famously reclusive, Ludwig almost never granted interviews. In 1985, he allowed himself to be photographed for the first time in 20 years. A 1986 biography of him was called "The Invisible Billionaire."
"He was a warm man with his friends, but he just wasn't interested in what the outside world thought of him," said Baker.
Ludwig is survived by his second wife, Gertrude, whom he married in 1937. His first marriage ended in divorce.
Funeral arrangements were private, Baker said.