As we head into a mid-summer lull in the primary action (the next competitive races are in August) it’s a good time to take stock of some of the trends we’re witnessing in campaigns across the country.

Internal strife in the Republican party has been driving national attention — and outside dollars — to GOP primaries across the country. These heated primaries, combined with a raft of competitive general elections, have combined to account for an eye-popping amount of third party spending. Super PACs and dark money groups have already been spent over $122 million on independent expenditures in the 2014 cycle. Sunlight found eight races where outside groups outspent the candidates themselves, including the recent Republican nail-biter in Mississippi.

No groups have spent more attacking other Republicans than the Club for Growth, Senate Conservatives, Ending Spending and FreedomWorks. Though the party’s conservative wing has scored a few notable upsets, campaign finance data from our Real-Time FEC tracker show just how little bang anti-establishment groups are getting for their collective buck. The bulk of their primary money, thus far, has been spent on losing candidates.

See their return on investment below:

Note: Successful primary spending in this graph is considered to be an expenditure supporting a candidate that won the party primary or an expenditure opposing a candidate that lost. Spending on the general election and primaries that have not been decided yet is not included in this data.

Conservative hopefuls like Matt Bevin in Kentucky, Chris McDaniel of Mississippi and and TW Shannon in Oklahoma all attracted outside dollars in droves, but these efforts all failed to translate to primary victories against well-funded incumbents.

None of these groups has fared worse than the Club for Growth Action, a super PAC that pushes limited government and fiscal conservatism. The committee poured over $3.1 million into the bitter Mississippi battle between Sen. Thad Cochran and Chris McDaniel — which Cochran ultimately won by a hair. That’s on top of nearly $500,000 that went toward unseating Rep. Mike Simpson, R-Idaho, which also came up short.

The only group to boast a “return on investment” of greater than 50 percent is Ending Spending Action Fund, spearheaded by TD Ameritrade founder Joe Ricketts. That’s mostly because the group devoted more than $1.1 million to attacking Georgia Rep. Phil Gingrey, R, who failed his bid to win the crowded GOP primary for retiring Sen. Saxby Chambliss’ seat.

Dark money accounts for a quarter of known outside spending

Though GOP primaries are the topic du jour, a liberal super PAC is 2014’s biggest mudslinger to date. The Senate Majority PAC has reported more than $16.8 million in independent expenditures this cycle — most of which has gone towards TV and radio ads aimed at Republicans in competitive general elections. Thanks to campaign disclosures made to the Federal Election Commission, however, we know that Senate Majority is fueled by massive checks from labor unions and liberal-leaning millionaires — but a whole lot of outside election spending has come from murkier sources.

Nearly one quarter ($30,059,556.74) of the $122 million in independent expenditures this cycle has come from groups like the conservative Chamber of Commerce ($11.5 million) or liberal Patriot Majority USA ($4.7 million) — nonprofit organizations that are not required to disclose their donors.

These totals don’t include nonprofit groups who have run electioneering ads slamming candidates more than 30 days before a primary election. Through the end of March, Americans For Prosperity spent more than $7 million attacking Sen. Kay Hagan (D-NC), none of which was reported to the FEC.

As OpenSecrets.org has detailed, the current election cycle is on track to be the darkest yet. With 19 states yet to hold primaries, the stream of dark money shows no signs of stopping. Check Real-Time FEC to see the latest independent expenditures and campaign disclosures in every race.