"movable receptacle for detached papers or prints," 1722, porto folio; 1719 as port folio, from Italian portafoglio "a case for carrying loose papers," from porta, imperative of portare "to carry" (from PIE root *per- (2) "to lead, pass over") + foglio "sheet, leaf," from Latin folium (see folio). Usually something like a book cover with a flexible back, fastened with strings or clasps. Meaning "official documents of a state department" is from 1835, hence figuratively, of a minister of state. A minister without portfolio is one not in charge of a particular department. Meaning "collection of securities held" is from 1930; portfolio investment is from 1955.