The Grand Slam of Thoroughbred racing is an informal name for winning four major Thoroughbred horse races in one season in the United States. The term has been applied to two configurations of races, both of which include the races of the Triple Crown—the Kentucky Derby, Preakness Stakes and Belmont Stakes—and either the Travers Stakes or the Breeders' Cup Classic as the final race.

The Travers Stakes Grand Slam is the older version, having been possible since 1875. These four races are sometimes also called the Superfecta or Quadruple Crown.^[1][2] The Breeders' Cup Classic Grand Slam has been possible since 1984.

Only one horse has won each configuration. Whirlaway won the Triple Crown and Travers Stakes in 1941, and American Pharoah won the Triple Crown and Breeder's Cup Classic in 2015.

The Grand Slam moniker is typically only available to three-year-old horses, as the Triple Crown and Travers Stakes are limited to that age. The Breeders' Cup Classic, however, has no age limits, so a Triple Crown winner could win the Classic in subsequent years, although that feat has yet to be attempted. It is unlikely to happen because Triple Crown winners are typically in high demand for stud service.

Quintuple Crown is the suggested name for winning all five races in the same season, a feat yet to be accomplished.

The Travers Stakes Grand Slam consists of the four oldest races for three-year-olds in the United States. The Travers was first run in 1864, followed by the Belmont in 1867, Preakness in 1873, and Derby in 1875. According to international classifications, the Travers is the third-ranked race for American three-year-olds, behind only the Kentucky Derby and Belmont Stakes.^[3] Racing historian Edward Hotaling first designated these four races as the Grand Slam.^[4]

Four horses that won the Triple Crown have attempted to complete the Grand Slam. Whirlaway accomplished the feat in 1941, while Gallant Fox (1930), Affirmed (1978) and American Pharoah (2015) came up short in their attempts. Due to the lack of success in winning the fourth race, the Travers Stakes has been nicknamed the "Graveyard of Champions."^[5]

Ten horses have won two legs of the Triple Crown and the Travers Stakes. Fifteen horses have entered all four races and won two or more. Three horses, Duke of Magenta, Grenada, and Man o' War did not enter the Kentucky Derby but won the three other races.

Nine Triple Crown winners did not enter the Travers Stakes. Secretariat withdrew before the race due to illness.^[6]

The Classic was first run in 1984, when the Breeders' Cup was inaugurated as a series of year-end championships.^[7] Unlike the Triple Crown races and the Travers Stakes, the Classic is not restricted to any age group and the Breeders' Cup has been hosted by several different tracks throughout its history.

For the first 32 runnings of the Classic, the Grand Slam was not in contention. In 2015, American Pharoah won the Triple Crown for the first time since 1978, making him the first horse eligible to compete for this configuration of the Grand Slam. Before the final race, sportswriter Bob Ehalt of ESPN declared American Pharoah was competing for the "Grand Slam," coining the second configuration of the term which quickly became popular.^[8][9] Pharoah won the Breeders' Cup Classic on October 31, 2015, and is the only horse to win this version of the Grand Slam.^[10]

This version of the Grand Slam differs from the Travers version because the Classic has no age restriction. Whereas the Triple Crown races and the Travers Stakes only adjust weight based on the horses' sex, the Classic also adjusts each horses' weight based on their age, a rule known as Weight for Age. Since the Breeders' Cup Classic was first run in 1984, most of the winners have been older than three-year-olds.^[11] Overall, fewer than half of the Classic winners of any age had entered any of the Triple Crown races when they were three-year-olds.^[11]

Only six horses have won at least one Triple Crown race and the Classic in the same three-year-old season, including Pharoah. Sunday Silence won the Derby, Preakness, and Classic, but was second in the Belmont.^[12] Four horses, Unbridled in 1990, A. P. Indy in 1992, Curlin in 2007, and Authentic in 2020, have won the Classic and one Triple Crown race.^[13][14][15]

Justify is the only horse to win the Triple Crown and not compete in the Breeders' Cup Classic. His owners and trainer planned to run him in the 2018 Breeders' Cup Classic, but an injury was discovered in July and Justify was retired from racing.^[16]

Three horses have won at least one Triple Crown race as a three-year-old and the Breeders' Cup Classic as a four-year-old. Alysheba won two legs of the Triple Crown in 1987 and the Classic in 1988.^[17] Two other horses have won one Triple Crown race and the Classic as a four-year-old: Ferdinand, winning the 1986 Derby and 1987 Classic, and Drosselmeyer, winning the 2010 Belmont and 2011 Classic.

In 1989, Sunday Silence and Easy Goer had a fierce rivalry, with both finishing in the top 2 each race. Sunday Silence beat Easy Goer by two-and-a-half lengths in the Derby, a nose in the Preakness, and a neck in the Breeders' Cup Classic. Easy Goer won the Belmont by eight lengths.^[18]

Racing historian Peter Lee has suggested winning all five races should be named the Quintuple Crown.^[19] While no horse has won all five races, several have competed in all five and won multiple since the Breeders' Cup Classic began in 1984. These include:

• Alyseheba, who in 1987 competed in all five races but only won the Derby and Preakness as a three-year-old. In 1988, Alyseheba entered the Breeders' Cup Classic again and won as a four-year-old.^[20]
• Tabasco Cat won the Preakness and Belmont.^[21]
• Easy Goer won the Belmont and Travers in 1989 but placed second in the Derby, Preakness, and Classic. The three losses were all close second-place finishes to rival Sunday Silence, who did not compete in the Travers.^[18]
• American Pharoah won the Triple Crown and Breeders' Cup Classic in 2015 but finished a close second in the Travers Stakes.^[22]

Note: Funny Cide competed in the 2003 Triple Crown and Breeders' Cup Classic but withdrew from the Travers due to illness. He won the Derby and Preakness.^[23]

• American thoroughbred racing top attended events
• Grand Slam of Grass
• Grand Slam (horse)
• Superfecta (betting)