The Mercer Family Foundation is a private 501(c)(3) philanthropic organization established by billionaire hedge fund manager Robert Mercer and his family, serving as their primary grantmaking vehicle. Funded largely by Mercer's wealth from Renaissance Technologies, the foundation is managed by Rebekah Mercer, a foundation director, and is a major funder of conservative and libertarian causes. It supports think tanks, policy organizations, advocacy groups, and media outlets, having contributed tens of millions of dollars to a network that forms a cornerstone of modern conservative infrastructure. Under Rebekah Mercer's direction, its focus shifted from traditional libertarian giving to more aggressive, anti-establishment causes. The foundation gained national attention for funding the rise of the alt-right and the populist movement that reshaped the Republican Party in the mid-2010s. Key beneficiaries include the Government Accountability Institute, producer of the film "Clinton Cash," and the Media Research Center. It has also been a major financier of organizations promoting climate change skepticism and immigration restriction. While the Mercer family's public profile in presidential politics has somewhat receded in recent years, the Mercer Family Foundation remains a significant source of funding for nationalist-conservative institutions.