late 14c., "to clothe in the official robes of an office," from Latin investire "to clothe in, cover, surround," from in "in, into" (from PIE root *en "in") + vestire "to dress, clothe," from PIE *wes- (2) "to clothe," extended form of root *eu- "to dress."
The meaning "use money to produce profit" is attested from 1610s in connection with the East Indies trade, and it is probably a borrowing of a special use of Italian investire (13c., from the same Latin root) via the notion of giving one's capital a new form. The figurative sense of "to clothe (with attributes)" is from c. 1600. The military meaning "to besiege, surround with hostile intent" also is from c. 1600. Related: Invested; investing.
Commercial sense of "an investing of money or capital" is from 1610s, originally in reference to the East India Company; general use is from 1740 in the sense of "conversion of money to property in hopes of profit," and by 1837 in the sense "amount of money invested." For evolution of the commercial senses, see invest.