David Koch, the conservative billionaire, activist and philanthropist, who gave more than $1 billion to charitable causes but was best known for using his money to reshape U.S. politics has died at the age of 79.

David, together with his brother, Charles, co-owned Koch Industries, a Nebraska-based energy and chemical company, since 1983. David stepped down from running the Koch organization last year due to declining health. A longtime New York resident, Koch was until retirement in June 2018 an executive vice president of the family company.

The Koch brothers are perhaps best known for building a massive conservative network of donors for organizations that work to mobilize voters and sway elected officials in support of libertarian-leaning economic policies.

In a prepared obit, the WSJ notes that "Koch, whose net worth of about $50.5 billion tied him with his brother as the world’s 11th-richest person in Forbes magazine rankings, gained most of his wealth from a 42% stake in Wichita, Kan.-based Koch Industries Inc., which has interests ranging from oil to beef to paper and is the second-largest closely held U.S. company."

Some more details from the WSJ:

Though he was a liberal on social issues like abortion and same-sex marriage, Mr. Koch used his fortune to support conservative causes that favor lowering taxes, free trade and fewer regulations. He was the Libertarian Party’s 1980 vice-presidential candidate. With his surviving older brother Charles Koch, the chairman and chief executive of Koch Industries, Mr. Koch created a network composed of like-minded wealthy donors brought together to back conservative causes. They were credited with helping finance the limited-government Tea Party movement that helped Republicans win control of the House in 2010 during President Obama’s first term. Their support of conservative causes became a lightning rod for Democrats, raising the ire of then-Sen. Harry Reid of Nevada, who in 2014 called Mr. Koch and his brother “un-American” and accused them of “trying to buy America” through campaign cash.

As the WSJ further notes, Megadonors such as the Kochs were able to grow their influence after the Supreme Court’s 2010 Citizens United decision, which allowed unlimited spending, both directly and indirectly, by outside groups

Diagnosed with prostate cancer in 1992, Koch had in recent years suffered from deteriorating health, according to the letter announcing his retirement from business and political activities. Over decades, Mr. Koch funneled some of his largest donations to cancer research, most notably to Memorial Sloan Kettering Cancer Center in Manhattan and to his alma mater, the Massachusetts Institute of Technology in Cambridge, Mass., for the founding of the Koch Institute for Integrative Cancer Research.

Koch attributed his philanthropy to a near-death experience in 1991, when an airplane he was in collided with another at Los Angeles International Airport. Mr. Koch was able to escape the smoke-filled plane, while more than 30 others were killed in the collision. Speaking about the crash in a 2014 television interview, Mr. Koch said, “I felt that the good Lord was sitting on my shoulder and that he helped save my life because he wanted me to do good works and become a good citizen.”

Born in Wichita on May 3, 1940, Koch attended public schools in his hometown before attending the prestigious Deerfield Academy in Deerfield, Mass. Mr. Koch earned his bachelor’s and master’s degrees in chemical engineering from MIT.

In addition to his brother Charles, Mr. Koch is survived by his three children; wife, Julia; twin brother, William Koch, and brother, Frederick Koch.