The inverted Jenny (or Jenny Invert) is a United States postage stamp of 1918 in which the image of the Curtiss JN-4 airplane in the center of the design was accidentally printed upside-down; it is probably the most famous error in American philately. Only 100 of the inverts were ever found, making this error one of the most prized in all philately; an inverted Jenny was sold at a Robert A. Siegel auction in June 2005 for US$525,000.