Thoroughbred horse racing is a worldwide sport and industry involving the racing of Thoroughbred horses. It is governed by different national bodies. There are two forms of the sport: Flat racing and jump racing, called National Hunt racing in the UK and steeplechasing in the US. Jump racing can be further divided into hurdling and steeplechasing.
Traditionally racehorses have been owned by very wealthy individuals. It has become increasingly common in the last few decades for horses to be owned by syndicates or partnerships. Notable examples include the 2005 Epsom Derby winner Motivator, owned by the Royal Ascot Racing Club, 2003 Kentucky Derby winner Funny Cide, owned by a group of 10 partners organized as Sackatoga Stable. 2008 Kentucky Derby winner Big Brown, owned by IEAH stables, a horse racing hedgefund organization.
Historically, most race horses were bred and raced by their owners. Beginning after World War II, the commercial breeding industry became significantly more important in North America, Europe and Australasia, with the result that a substantial portion of Thoroughbreds are now sold by their breeders, either at public auction or through private sales. Additionally, owners may acquire Thoroughbreds by "claiming" them out of a race (see discussion of types of races below).
A horse runs in the unique colours of its owner. These colours must be registered under the national governing bodies and no two owners may have the same colours. The rights to certain colour arrangements ("cherished colours") are valuable in the same way that distinctive car registration numbers are of value. It is said that Sue Magnier (owner of George Washington, Galileo etc.) paid £50,000 for her distinctive dark blue colours. If an owner has more than one horse running in the same race then some slight variant in colours is often used (normally a different coloured cap) or the race club colours may be used.
The horse owner typically pays a monthly retainer or, in North America, a "day rate" to his or her trainer, together with fees for use of the training center or gallops (if the horse is not stabled at a race track), veterinarian and farrier (horseshoer) fees and other expenses such as mortality insurance premiums, stakes entry fees and jockeys' fees. The typical cost of owning a race horse in training for one year is in the order of £15,000 in the United Kingdom and as much as $35,000 at major race tracks in North America.