The Inverted Jenny is a 24 cent United States postage stamp first issued on May 10, 1918, in which the image of the Curtiss JN-4 airplane in the center of the design is printed upside-down; it is probably the most famous error in American philately. Only one pane of 100 of the invert stamps was ever found, making this error one of the most prized in philately.
A single Inverted Jenny was sold at a Robert A. Siegel auction in November 2007 for $977,500.
 
On 15 November 2018, the recently discovered position number 49 stamp was auctioned by Robert A. Siegel Auction Galleries for a new record hammer price of $1,350,000, with an 18 percent buyer's premium raising the total cost to US$1,593,000.