The number of registered Thoroughbreds for the 4th generation sires on the top sire line pedigree for the registered foals of 2021.
| Sire Name | Registered Thoroughbreds |
|---|---|
| Mr. Prospector | 3096 |
| Seattle Slew | 1276 |
| Northern Dancer | 1265 |
| A.P. Indy | 1154 |
| Storm Cat | 1101 |
| Fappiano | 875 |
| Storm Bird | 874 |
| Sadler's Wells | 827 |
| Raise a Native | 698 |
| Bold Reasoning | 656 |
| Harlan | 614 |
| Cryptoclearance | 612 |
| Unbridled | 604 |
| Hennessy | 576 |
| Gone West | 480 |
| Siberian Express | 442 |
| In Excess (IRE) | 437 |
| Halo | 328 |
| Vice Regent | 268 |
| Hail to Reason | 262 |
| Relaunch | 224 |
| Nearctic | 212 |
| Tale of the Cat | 211 |
| Dixieland Band | 208 |
| Forty Niner | 195 |
| Roberto | 155 |
| Wavering Monarch | 149 |
| Machiavellian | 123 |
| Danzig | 113 |
| Gulch | 92 |
| Deputy Minister | 85 |
| Raja Baba | 71 |
| Seeking the Gold | 67 |
| Ride the Rails | 63 |
| Great Above | 62 |
| In Reality | 39 |
| Native Dancer | 31 |
| Cee's Tizzy | 26 |
| Quiet American | 26 |
| Afleet | 25 |
| Caro (IRE) | 25 |
| Blushing Groom (FR) | 24 |
| Kris S. | 23 |
| Majestic Light | 21 |
| Buckpasser | 19 |
| El Prado (IRE) | 18 |
| Minnesota Mac | 17 |
| Fortino II (FR) | 15 |
| His Majesty | 15 |
| Southern Halo | 14 |
| Valid Appeal | 14 |
| Battle Joined | 13 |
| Carson City | 13 |
| Red God | 13 |
| Icecapade | 12 |
| Damascus | 11 |
| Milkie's Desire | 11 |
| Private Account | 10 |
| Boldnesian | 9 |
| Cormorant | 9 |
| Buckaroo | 8 |
| Intentionally | 6 |
| Super Concorde | 5 |
| Ack Ack | 4 |
| Alydar | 4 |
| Bailjumper | 4 |
| Clever Trick | 4 |
| Conquistador Cielo | 4 |
| Milkie | 4 |
| Pulpit | 4 |
| Sword Dancer | 4 |
| Foolish Pleasure | 3 |
| Green Desert | 3 |
| Runaway Groom | 3 |
| Best Turn | 2 |
| Bold Ruler | 2 |
| Codex | 2 |
| Deer Lodge | 2 |
| Johannesburg | 2 |
| Literat (GER) | 2 |
| Lord At War (ARG) | 2 |
| Miswaki | 2 |
| Mt. Livermore | 2 |
| Niniski | 2 |
| Sky Classic | 2 |
| Skywalker | 2 |
| Sonny's Solo Halo | 2 |
| Cherokee Run | 1 |
| Cyane | 1 |
| Dewan | 1 |
| Explodent | 1 |
| Fairy King | 1 |
| For The Moment | 1 |
| Gallant Romeo | 1 |
| Giant's Causeway | 1 |
| Go for Gin | 1 |
| Gold Apollo | 1 |
| Good Manners | 1 |
| Hold Your Peace | 1 |
| Jack Sprat | 1 |
| Lorenzaccio | 1 |
| Mill Reef | 1 |
| Nijinsky II | 1 |
| Northern Afleet | 1 |
| Phone Trick | 1 |
| Private Terms | 1 |
| Ribot | 1 |
| Sovereign Dancer | 1 |
| Unbridled's Song | 1 |
| Whiskey Road | 1 |
Source: The Jockey Club
Current through 4/29/2024