To attain or maintain a Group One status, the average rating for the first four finishers in the race must be 115 or higher over a three-year period.
[2] Group One races may only be restricted to age groups or a stipulated sex: they should not be restricted to horses bred in a certain country (though there are regional exceptions to this rule).
[4] In the United States, Canada, Japan, South Africa, and British National Hunt racing "Grade I" is used instead; see List of British flat horse races.
[5] These races, whether designated as "Group One" or "Grade I", are of international importance[4] and attract the best horses.
For example, the minimum purse for a Grade I race in North America in 2016 was $300,000.