What does Boxing Day have to do with boxing?
to finance something to an excessive degree; to provide more funding than is necessary or allowed
The governor's campaign is overfunded.
1660s, from French fond "a bottom, floor, ground" (12c.), also "a merchant's basic stock or capital," from Latin fundus "bottom, foundation, piece of land," from PIE root *bhudh- "bottom, base" (cf. Sanskrit budhnah, Greek pythmen "foundation, bottom," Old English botm "lowest part;" see bottom (n.)). Funds "money at one's disposal" is from 1728. Fund-raiser (also fundraiser) first attested 1957.
1776, from fund (n.). Related: Funded; funding.