Since it is the race most North American Thoroughbred breeders aspire to win, the Kentucky Derby (G1) provides a useful snapshot of current commercial sire lines. With that in mind, we'll look at the sire lines of this year's runners, along with some recent historical context.
Raise a Native and Mr. Prospector
This century, the Mr. Prospector line has been the dominant force, with 12 Kentucky Derby winners, including three from the Smart Strike branch and three from the Fappiano line, including a Triple Crown winner, American Pharoah. The Mr. Prospector line first scored with Unbridled (by Fappiano) in 1990, followed by further 20th-century successes for Thunder Gulch (by Gulch) in 1995, Grindstone (by Unbridled) in 1996, and Real Quiet (by Quiet American, a son of Fappiano) in 1998. Remarkably, Mr. Prospector himself wasn't represented by his first Kentucky Derby winner until 2000, when Fusaichi Pegasus, conceived when Mr. Prospector was 26 years old, triumphed.
This year, at the time of writing, there are five Kentucky Derby contenders from the Mr. Prospector line. Three of these are from the Fappiano branch: Emerging Market is by Candy Ride , a son of Ride the Rails, who was by Fappiano's son Cryptoclearance; and Further Ado is by Candy Ride's son, Gun Runner . From the Unbridled branch comes Fulleffort, by Liam's Map, who is by Unbridled's Song (a son of Unbridled). Golden Tempo comes from the Smart Strike branch via Curlin , whose sons Keen Ice and Good Magic are both sires of a Kentucky Derby winner, Rich Strike (2022) and Mage (2023). Finally, Japanese challenger Danon Bourbon is a son of Maxfield , by the 2007 Kentucky Derby victor Street Sense , whose own sire, Street Cry, was by Mr. Prospector's European-raced son, Machiavellian.
Mr. Prospector was by Raise a Native, and three other branches of Raise a Native appear in the sire line of Kentucky Derby winners. The only Kentucky Derby winner sired by Raise a Native himself was Majestic Prince (1969). Majestic Prince's grandson, Wavering Monarch, was responsible for Maria's Mon, the champion 2-year-old of 1995, and sire of a pair of Kentucky Derby winners in Super Saver and Monarchos. The line is represented in this year's Derby by Californian hopeful So Happy, who is by Super Saver's son, Runhappy, the champion male sprinter of 2015.
Two other branches of Raise a Native, which have effectively vanished from mainstream North American pedigrees, also provided Kentucky Derby winners. Exclusive Native had a historic impact with a Triple Crown winner, Affirmed in 1978, and the second-ever filly winner, Genuine Risk in 1980. Alydar, runner-up to Affirmed in all three legs of the Triple Crown, sired the winners in 1987 and 1991, Alysheba and Strike the Gold.
Northern Dancer
Northern Dancer was retired to stud seven years earlier than Mr. Prospector, but he took longer to make an impact on his first classic, and it wasn't until 1986 that the first Northern Dancer-line horse wore the roses, Ferdinand (by Nijinsky II). The line then added just two more in the rest of the century: Sea Hero in 1993, by Danzig son Polish Navy, and Charismatic in 1999, by Summer Squall.
After that, the next Northern Dancer-line representative didn't appear until 2008, when Big Brown, by another Danzig horse, Boundary, won. Since then, however, five of the last 17 winners—all in the last eight years—have sprung from the Northern Dancer line, all five descending from Storm Cat, who himself never sired a Derby winner. Three of those, Authentic (2020), Mandaloun (2021), and Sovereignty (2025), are by Into Mischief , by Harlan's Holiday, by Harlan; and a fourth, Mystik Dan (2024), is by Into Mischief's son Goldencents . Before that quartet, however, came Triple Crown hero Justify (2018). He was by Scat Daddy, a very successful sire but otherwise most noted for his turf runners, by "world champion 2-year-old" Johannesburg, a son of Hennessy.
This year's Derby lineup will feature seven Northern Dancer-line horses, six from the Storm Cat line. Four of those stem from the Into Mischief branch: Renegade, Commandment, and Potente by Into Mischief himself, and Intrepido by Into Mischief's son Maximus Mischief . The other two Storm Cat-line hopefuls are descendants of three-time leading sire Giant's Causeway: the likely pace factors Pavlovian (Pavel , by Creative Cause ) and Six Speed (by Not This Time ).
The seventh Northern Dancer-line horse in the field is Incredibolt. He descends from Northern Dancer's greatest stallion son, Sadler's Wells, through 1991 Irish champion 2-year-old El Prado, Medaglia d'Oro, and Bolt d'Oro .
Nasrullah
Nasrullah, champion sire in England and Ireland in 1951 and five-time leading sire in North America, is in the sire line of five 21st-century Kentucky Derby winners. Through his eight-time leading sire son Bold Ruler, via Boldnesian, Bold Reasoning, and Seattle Slew, he is represented by A.P. Indy. Second favorite at the time, A.P. Indy was scratched on the morning of his intended Derby start in 1992 because of a foot problem, but he returned to take the Belmont Stakes (G1) and Breeders' Cup Classic (G1). Despite his outstanding success at stud with classic-distance runners, A.P. Indy never sired a Kentucky Derby winner, the closest being Aptitude, second in 2000. Ultimately, it wasn't until 2013, 21 years after A.P. Indy's own 3-year-old season, that the first horse from the A.P. Indy male line captured the Derby, that being Malibu Moon's son, Orb. The following year, an A.P. Indy-line horse from a less-expected source carried the day, with the victory of California Chrome , by the California-based Pulpit son Lucky Pulpit.
Pulpit is also the channel through which A.P. Indy appears in the direct sire line of four of Saturday's intended runners. All four go back to Pulpit's son Tapit . Two of these are via the Tapit horse Constitution , his sons Chief Wallabee and Right to Party. The other A.P. Indy-line representatives are The Puma, from the first crop of Tapit's dual champion Essential Quality , and Silent Tactic, from the first crop of Tapit son Tacitus .
The other branch of Nasrullah represented in this year's Run for the Roses is that of Caro, a grandson of Nasrullah's foul-tempered sprinting son Grey Sovereign, a three-quarter brother to the 1949 Epsom Derby victor Nimbus. The French-raced Caro was imported to the U.S. and notably sired Winning Colors, who, in 1988, became only the third filly to capture the Kentucky Derby. His sire line comes down through Siberian Express, In Excess, Indian Charlie, and Uncle Mo. Champion 2-year-old male of 2010, Uncle Mo sired a Kentucky Derby winner in Nyquist (2016), and Nyquist is the sire of this year's Kentucky Derby runner Litmus Test. Uncle Mo is also responsible for Yaupon , the leading freshman sire of 2025 and current leading second-season sire, who will be represented by Albus.
Nasrullah's three-quarter brother Royal Charger was also imported, and he founded a sire line that comes down via Turn-to/Hail to Reason. Hail to Reason's son Halo sired a pair of Kentucky Derby winners: Sunny's Halo (1983) and Sunday Silence, who scored in 1989 before his export to Japan, where he became a breed-shaping influence. The Sunday Silence branch of Halo came extremely close to a Derby triumph in 2024 with Forever Young (by Real Steel, by Sunday Silence's outstanding son Deep Impact), and this year the line is represented by another Deep Impact grandson, Wonder Dean (by Dee Majesty).
End of the Line
Equally interesting as the sire lines supplying this year's Kentucky Derby runners is the identity of lines that recently supplied winners of the race but appear unlikely to do so again. In the last 20 years of the 20th century, there were three from the Buckpasser line (Spend a Buck in 1985, Lil E. Tee in 1992, and Silver Charm in 1997), two winners from the Ribot line (Pleasant Colony in 1981 and Go for Gin in 1994), and, as a real outlier, the Chilean-bred Cougar II, a grandson of the 1944 English St. Leger winner Tehran.
In this century, Kentucky Derby winners who may well be the last of the line include Barbaro (2006), from the Roberto branch of Hail to Reason; Animal Kingdom (2011), from the Blushing Groom branch of Nasrullah; and Giacomo (2005), from America's oldest native sire line—Eclipse via Alarm and Himyar—and a son of Holy Bull, who does still have a proven grandson in Mucho Macho Man , who has sired two grade 1 winners.
