1. Tom Steyer
Tom Steyer, who made his fortune running Farallon Capital, has not been shy about speaking out against Trump or spending his vast fortune to get him out of office.
Steyer has been one of the loudest voices calling to impeach the President and gave $72.5 million to different Democratic candidates and PACs.
He viewed the midterm elections as critical to a possible impeachment, telling CNBC before the election that "we're screwed" if the Democrats didn't perform well. The Democrats ended up re-taking the House of Representatives.
2. Donald Sussman
Donald Sussman, the founder of Paloma Partners, was a big Hillary Clinton backer in 2015 and 2016. In the midterms, he spent more than $22 million in 2017 and 2018 to break Republicans' hold on the House of Representatives.
Sussman, whose investment in D.E. Shaw in the 1980s helped launch the quant giant, was the fifth biggest individual donor in the midterm election cycle, according to Public Citizen.
3. Jim and Marilyn Simons
Donating more than $20 million between them, Jim and Marilyn Simons were the sixth-biggest political donors in the 2018 election cycle.
Jim Simons, who created secretive quant fund Renaissance Technologies, can certainly afford it: Simons made $1.6 billion in 2018, despite stepping away from day-to-day leadership of the fund nearly a decade ago.
4. Ken Griffin
Citadel founder Ken Griffin, who told an audience at the Milken conference last month that "soaking the rich doesn't work," was the third-biggest donor to Republicans in the 2018 midterm elections.
Griffin, who bought the country's most expensive apartment ever sold earlier this year, gave more than $18 million to support conservative politicians.
See more: Inside the Chicago hedge fund turf war between billionaire Ken Griffin and Dmitry Balyasny
5. George Soros
George Soros, who turned his hedge fund into a family office in 2011, has been the target of conservative politicians and media for donating to foundations working toward criminal justice and immigration reform.
Soros, who was born in Hungary and survived Nazi rule there as a child, donated nearly $17 million in the cycle. His son, Alex, and daughter, Andrea, also made the list, donating a combined $4 million to Democratic causes.
6. Seth Klarman
Boston billionaire Seth Klarman was once the biggest Republican donor in the state of Massachusetts, but has been vocal against Trump. His spending reflects his distaste with the current administration, as he gave more than $5 million to support Democrats.
He told The New York Times in 2018 that he thinks "democracy is at stake" with Trump at the helm. He donated to candidates in swing districts like Conor Lamb as well as Beto O'Rourke's failed campaign to win one of Texas' Senate seats from Ted Cruz.
7. Paul Singer
Elliot Management CEO Paul Singer, known for his clashes with foreign governments, is a big supporter of the Republican, but not Trump initially. He supported Florida Sen. Marco Rubio in the primaries, before eventually donating to Trump's inauguration fund.
He has met with Trump in the White House since, telling an audience in 2017 that he "became optimistic about some of the opportunities in economic growth and regulatory reform, tax reform." Singer gave more than $5 million in the midterms cycle.
8. Henry Laufer
Ten years after Henry Laufer retired from Renaissance Technologies, he is putting his wealth to work for Democrats. The former chief scientist for the secretive quant fund gave roughly $4.5 million during the midterm cycle.
Laufer helped start the the Long Island-based hedge fund with Jim Simons, another large donor to Democrats. Laufer and his wife Marsha, who held a $500-a-plate fundraising dinner for Hillary Clinton in Florida in 2016, donated to several PACs supporting female candidates.
9. Robert Mercer
Seemingly to balance out the large donations made to the other side by Simons and Laufer, former Renaissance Technologies co-CEO Robert Mercer has been one of the biggest Republican donors the last few elections.
Mercer, who originally supported Sen. Ted Cruz for president, has been supportive of Trump, and was a main backer of right-wing Brietbart News, which has supported the president's immigration agenda. Mercer gave $4.3 million in the most recent election cycle.
10. Steve Cohen
Steve Cohen, the billionaire founder of Point72, was a big backer of former New Jersey Gov. Chris Christie's run for president, and, in the most recent election cycle, gave millions to make sure Republicans did not lose control of the Senate.
In total, Cohen gave $3.1 million in the last cycle, according to the report.
11. William Oberndorf
SPO Partners co-founder William Oberndorf gave $2.2 million to Republicans during the midterms. Oberndorf's hedge fund, $5 billion SPO Partners, closed in late 2018.
Oberndorf was a big supporter of former Florida Gov. Jeb Bush during the primaries, and told The New York Times that he would be voting for Clinton over Trump in the election. Since the election, he has sought, similar to Singer, to support more moderate Republicans in primary races. He has also supported California democratic Sen. Dianne Feinstein.
He also donated to nearly $50,000 in 2016 to support the controversial Proposition Q in San Francisco, which banned tents on sidewalks. It proposition, which was passd, was criticized by activists for criminalizing homelessness.
12. Louis Moore Bacon
After donating across the political spectrum before the 2016 election, Moore Capital Management founder Louis Moore Bacon put his personal fortune to work for Democrats in 2018.
The hedge fund founder gave $1.75 million to primarily Democrats and left-leaning PACs. In 2016, he backed several Republican senators up for re-election like Pennsylvania Sen. Pat Toomey and North Carolina Sen. Richard Burr. He also gave, in 2016, to Colorado Sen. Michael Bennet, who is a part of the deep field of Democrats running for president in 2020.
13. David Shaw
Spending $1.4 million, David Shaw backed Democrats in the most recent election cycle, according to the report.
The quant fund billionaire gave millions to Hillary Clinton's main PAC for the 2016 election, and supported several down-ballot female candidates for Congress, including Zephyr Teachout, a Fordham law professor who has supported increasing taxes on the country's richest.
14. Stephen Mandel
Stephen Mandel, a disciple of Julian Robertson who stepped back from running Lone Pine Capital at the beginning of the year, gave money to back Democrats in 2018. In total, Mandel gave $1.4 million.
His past donations imply that education is one of his biggest focuses. His foundation has backed charter school expansion in Connecticut, and Mandel has sat on the board of Teach For America.
15. Dan Loeb
Third Point founder Dan Loeb has given to both sides of the political spectrum, but in the 2018 midterms, Loeb primarily focused on giving to Republicans, according to the report.
Loeb gave just over $1 million during the cycle; his activist fund most recently made headlines over a near proxy fight with Campbell Soup Co.