- Who
- Bill Gross, Donald Sundman
- What
- 2970000 US dollar(s)
- Where
- United States ()
- When
In October 2005, Bill Gross (USA) traded his block of four 'Inverted Jenny' airmail stamps - which he had just bought for $2.97 million (£1.67 million) - for a one-cent Z-grill belonging to Donald Sundman (USA). The 1868 Z-grill, depicting Benjamin Franklin and named after the security grill used to prevent the postmark being washed off, is amongst the most expensive stamps in the world, having been bought by Mr Sundman in 1988 for $930,000 (then £520,800), but valued in 2005 at $3 million (£1.7 million). It is the only privately-owned Z-grill - the only other copy is owned by the New York Public Library. The 'Inverted Jenny' is amongst 100-known stamps misprinted in 1918 with the Curtiss JN4H biplane flying upside-down.
