His previously unreported $4.3 billion gift to Believe in People is now the largest publicly disclosed donation to a 501(c)4–a type of nonprofit with fewer restrictions on lobbying and politics than traditional charities.

Charles Koch is making big moves to ensure that his charities and causes are funded long after hes gone. In an exclusive interview, the 87-year-old chairman and co-CEO of Koch Industries (and the 16t…