Democratic presidential nominee Hillary Clinton's September inundation of the airwaves cost her campaign $66 million, swamping rival Donald Trump's media presence.

A new campaign finance report filed Thursday night showed that Clinton's campaign committee paid out nearly $66 million for media buys last month to the ad placement firm GMMB — twice as much it spent in August.

Clinton's media investment was almost triple the $23 million that Trump spent to put ads on the air in September. Trump's campaign shelled out nearly $21 million more on digital consulting and online ads, while Clinton's committee spent $866,000 on online ads. But Hillary Victory Fund, a joint fundraising committee between the campaign and the Democratic Party, spent another $26 million on online ads over the last three months, filings show.

Clinton spent a total of nearly $95 million through her campaign and two joint fundraising committees in September, exceeding the $85 million in campaign contributions raised through all three entities. About 27 percent of her money came from contributions of $200 or less.

When October began, she still had more in her campaign coffers than Trump: $59 million to his $34.7 million.