The highest price paid for a thoroughbred race horse at public auction is $16 million (then £9.1 million) for a two-year-old, then unnamed colt, who had yet to even race. The Forestry colt was bought through an agent, Demi O'Byrne (Ireland), in the auction held at Calder Race Course, Florida, USA on 28 February 2006.
The bay colt, (with a white blaze) was bred in Florida, USA and sold at auction the year before (July 2005) for $425,000 (then £244,000).
('Forestry' refers to its pedigree - see attachment).
Comments below may relate to previous holders of this record.