Wallpaper is the name given to stocks, bonds, and other securities that have become worthless. This colloquialism saw its beginnings when stocks and bonds existed as printed, physical certificates rather than digital identifying information stored on a brokerage's server.

The name stuck, however, and denotes when a stock or bond certificate (or another exercisable right to securities such as stock options) no longer has value due to a variety of reasons, most commonly, bankruptcy.