Billionaire George Soros donated $6 million dollars last month to a super PAC supporting Hillary Clinton, according to FEC documents filed Sunday.

In total, the Hungarian-born financier contributed $8 million dollars to pro-Clinton super PACs in 2015. The mid-December contribution of $6 million to Priorities Action USA added to a $1 million donation he made earlier in the year. He gave another $1 million to American Bridge 21st Century.

Soros, who is chairman of Soros Fund Management, is a longtime contributor to Democratic campaigns. He supported John Kerry's presidential run in 2004, and Obama's campaign in 2008 and reelection campaign in 2012.

Priorities Action USA raised $41 million total in 2015, with about $35 million left in the bank heading into election year 2016.