Presidential candidates on Wednesday filed campaign-finance disclosures showing how much money they had raised and who was bankrolling their campaigns. But their filings also offered a window into another key metric: How quickly campaigns are burning through their cash.

Of the eight candidates who have so far filed their disclosures with the Federal Election Commission, Republicans Ben Carson and Rick Santorum have spent the largest shares of the money they raised—64% and 62%, respectively. The Carson campaign spent the bulk of its $8.5 million raised in the second quarter on fundraising costs, an official said. The Santorum operation spent nearly a quarter of the $395,000 it spent on direct mail and website development.