The Republican presidential nominee's campaign ended June with more than $20 million on hand, a big jump from $1.3 million at the end of May. Clinton's campaign committee reported more than double that, with $44.4 million on hand.
The campaign for Trump, who is expected to accept the Republican nomination here Thursday, reported nearly $27 million in total receipts, according to the Federal Election Commission report filed Wednesday. Clinton's campaign had more than $36 million in receipts.
The Trump campaign's operating expenditures increased to $7.8 million from $6.7 million in May. Still, they fall far below what candidates would typically spend in the lead up to an election. Clinton's campaign spent about $34 million in June.
The report comes as both campaigns gear up fundraising efforts in the general election push.
Trump followed through on his pledge to forgive about $47.5 million in loans to his campaign. The committee also took in more than $2 million from joint fundraising efforts with the Republican Party.
The Trump campaign has so far spent very little relative to most of its Republican and Democratic opponents. It has gotten by largely on loans from Trump himself, and the Clinton campaign had outspent it on ads by more than $40 million as of earlier this month. A heavy dose of free media also has aided the Trump campaign along the way.
Trump's recent choice of Indiana Gov. Mike Pence as his running mate adds another wrinkle to his fundraising efforts, according to the Center for Responsive Politics. The Securities and Exchange Commission's so-called pay to play rule stops "SEC registered investment advisers" from giving more than $250 to $350 to state or local officials who could choose who manages a pension fund, which could apply to Pence.
That may hold back many hedge funds and private equity firms from giving to the Republican ticket.
UPDATED: This story was updated to include information from Hillary Clinton's FEC filing.