Almost $465m of outside money has been spent on the US presidential election campaign so far, including $365m that can be attributed to the supreme court’s landmark Citizens United ruling, according to a report released on Monday.

Super Pacs, which came into effect following the 2010 Citizens United verdict, accounted for $272m of the expenditure in the study, conducted by the Sunlight Foundation, a non-profit organisation devoted to increasing transparency in government.

A further $93m has been spent by corporations, trade associations and non-profits which, according to the supreme court’s decision, are able to spend unlimited amounts on political campaigning without disclosing the source of their funds.