Elon Musk poured about $75 million last quarter into the super PAC supporting Donald Trump’s presidential campaign, according to a new campaign finance filing.

Musk, the world’s richest man, was the only donor to the pro-Trump America PAC, according to a filing with the Federal Election Commission late Tuesday. Musk launched the group over the summer and has funded outreach to voters in key presidential states and more than a dozen House races.

That’s a staggering amount from one man — though it certainly doesn’t dent Musk’s personal fortune, and it’s not even enough to make him the biggest pro-Trump donor. Longtime Republican donor Miriam Adelson has given $100 million to another Trump-boosting super PAC, Preserve America, while banker Timothy Mellon has given $125 million to a third super PAC, Make America Great Again Inc.

Elon Musk has become an increasingly integral part of Trump’s campaign, deciding to back the former president after the assassination attempt on him in July.

What are super PACs?

Super PACs (Political Action Committees) can raise unlimited amounts of money from corporations, unions, associations, and individuals and then spend unlimited amounts to openly support political candidates, or openly turn against them. Unlike traditional PACs, super PACs are prohibited from donating money directly to political candidates and their spending must not be coordinated with that of the candidates they benefit. Super PACs are required to regularly report their donors to the Federal Election Commission.