The Jockey Club projects a North American registered Thoroughbred foal crop of 16,500 in 2027, down from its estimate of 17,000 for 2026.
The foal crop projection is computed by using reports of mares bred received to date for the 2026 breeding season. RMBs are to be filed by Aug. 1 of each breeding season.
For the RMBs received through Oct. 1, 2026, The Jockey Club reports that 670 stallions covered 23,932 mares in North America during 2026.
The Jockey Club estimates an additional 2,000 to 3,000 mares will be reported as bred during the 2026 breeding season.
Of the RMB reports received, 180 mares were part of the mare incentive program, which waives registration fees for certain 2027 foals of mares that meet criteria defined by The Jockey Club. This initiative was announced in December 2024 to stimulate interest in mares who appear to have left production.
The following table shows the number of covering stallions and the number of mares bred in the last five years in North America as reported to The Jockey Club through October 1 of the breeding year.
| 2022 | 2023 | 2024 | 2025 | 2026 | |
| Stallions | 880 | 825 | 771 | 738 | 670 |
| Mares bred | 26,744 | 26,202 | 25,263 | 24,662 | 23,932 |
Kentucky traditionally leads North America in Thoroughbred breeding activity. During 2026, Kentucky’s 187 reported stallions covered 16,677 mares, or 69.68% of all mares reported bred in North America.
The following table shows a segmentation of the number of mares bred by stallion for 2026 as reported to The Jockey Club through October 1, 2026.
| Mares bred per stallion | 1–49 | 50–99 | 100–149 | 150–199 | 200–249 | 250+ |
| Number of stallions | 519 | 73 | 34 | 27 | 13 | 4 |
The following stallions covered 200 or more mares: Sierra Leone had the highest number of mares bred in 2026, with 293. He was followed by Tiz the Law (288), Citizen Bull (261), Gun Runner (250), Gunite (236), Not This Time (230), Drain the Clock (227), Locked (226), Vekoma (224), Girvin (223), Golden Pal (221), Practical Joke (219), Corniche (216), Yaupon (214), Barnes (211), Justify (205), and Goal Oriented (201).
The 2025 breeding statistics, which include data for live foal reports for the 2026 foaling season, will be released later this month.
The Jockey Club has historically released RMB statistics without commentary. This year, alongside the data, we are sharing our view of what the numbers show in an effort to think through new programs and initiatives that can drive meaningful results. Figures in this section reflect mares reported bred in North America through Oct. 1, 2026, compared with the same point in 2025.
North American breeding continued to contract, but the stallion population declined even faster.
Through Oct. 1, 23,932 mares were reported bred in North America in 2026, down 3.0% from 24,662 at the same point in 2025. In the same period, the number of reported stallions fell 9.2%, from 738 to 670. As a result, the average book size increased from 33.4 mares per stallion to 35.7 mares per stallion, reflecting continued concentration in the breeding market.
| Through Oct. 1 | 2025 | 2026 | Change |
| North American mares bred | 24,662 | 23,932 | −3.0% |
| North American stallions | 738 | 670 | −9.2% |
| Average book, mares per stallion | 33.4 | 35.7 | 2.3 mares |
| Kentucky mares bred | 16,370 | 16,677 | 1.9% |
| Kentucky stallions | 189 | 187 | −1.1% |
| Kentucky share of North American mares bred | 66.4% | 69.7% | +3.3 pct pts |
| Mares bred outside Kentucky | 8,292 | 7,255 | −12.5% |
| Stallions outside Kentucky | 549 | 483 | −12.0% |
