Dubbed the “billionaire election” by some, these midterms have featured more money than ever spent by the wealthiest Americans and less by small donors. Big-spending outside groups are distilling an already elite donor pool even further, according to the Center for Responsive Politics, and the overall number of individual donors has declined for the first time.

Listed below are the top five donors to unrestricted super PACs in both parties, as ranked by the Sunlight Foundation. Not included are contributors to tax-exempt advocacy groups that operate outside the disclosure rules, such as the billionaire industrialists Charles and David Koch.

After more than two decades at the helm of the Farallon Capital hedge fund, Steyer is shoveling tens of millions into his environmental super PAC, NextGen Action Fund. With close to $74 million in donations so far, the Sunlight Foundation has dubbed Steyer “the largest single contributor to a super PAC of all time.” He has also given $5 million to the Democratic Senate Majority PAC.

A former New York City mayor, philanthropist and founder of Bloomberg LP, Bloomberg has put more than $7 million into his super PAC, Independence USA, and he has invested heavily in Everytown for Gun Safety, an organization he helped found that focuses on both advocacy and elections. Bloomberg has also given $2.5 million to Senate Majority PAC and another $2 million to Women Vote, the super PAC run by EMILY’s List.

Eychaner, the CEO of Newsweb Corp., has long been a top Democratic donor. In the 2012 elections, he bundled more than $500,000 for President Barack Obama and Democratic Party committees. This cycle, his top contributions include $5 million to the Senate Majority PAC and $2.5 million to House Majority PAC.

A hedge fund billionaire, investor, philanthropist and top Democratic donor, Soros has upped his political contributions from 2012, when he gave $1.3 million. This time, Soros has more than doubled his contributions with six- and seven-figure donations made through Soros Fund Management, to American Bridge 21st Century, House Majority PAC and the League of Conservation Voters Victory Fund, among others. Soros also has contributed to Democratic Party committees and several dozen Democratic candidates.

Simons has retired from, but remains active with his Renaissance Technologies hedge fund. A former defense Department code breaker, Simons has donated more than $1 billion to his Simons Foundation. In this cycle he’s given $2 million to Senate Majority PAC and $1 million to House Majority PAC.

As founder of the Elliott Management hedge fund, Singer is a leading GOP donor who supports gay marriage. He’s given multiple three- to six-figure contributions to the American Unity PAC and the Ending Spending Action Fund, two super PACs backing Republicans, plus $1.4 million to American Crossroads.

The co-CEO of Renaissance Technologies, Mercer has been listed by Forbes magazine as one of the nation’s highest-earning hedge fund managers, with 2011 earnings of $125 million. This cycle, he’s given $2.5 million to Freedom Partners Action Fund, the new super PAC linked with the Koch brothers, and backed several other conservative and tea-party-focused super PACs, including the John Bolton Super PAC; Club for Growth Action; Senate Conservatives Action and the American Heartland PAC.

The chairman and CEO of the Las Vegas Sands, Adelson has spent far less in 2014 — in disclosed campaign money, at least — than he did in 2012. In the previous elections, Adelson spent by various estimates at least $100 million to try to help elect Republican Mitt Romney and other Republicans, through both publicly reported and undisclosed avenues. This cycle, he has contributed just $5 million in hard money to the Congressional Leadership Fund, which supports House Republican candidates.

Ricketts is founder of the online brokerage TD Ameritrade. His family owns the Chicago Cubs and Wrigley Field, and he started a foundation to promote education in developing nations. A loyal GOP donor, Ricketts has given more than $1 million this cycle to the Ending Spending Action Fund, a pro-GOP super PAC that he launched.

Uihlein, who owns the Uline Inc. shipping and packaging company, is a conservative donor with a strong tea party bent. The Sunlight Foundation has identified him as Illinois’ largest GOP donor, and he has given millions to a long list of tea party candidates, groups and causes. These include Club for Growth Action, Senate Conservatives Action, Madison Action Fund and Liberty Principles PA.

* Estimate based on news reports in the Chicago Tribune and elsewhere.

Sources: Forbes Magazine Billionaires List, FEC data compiled by the Sunlight Foundation and the Center for Responsive Politics.

Correction Nov. 6, 3:50 p.m.

An earlier version of this story misspelled Mitt Romney’s last name.

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