Definitely not a fixed cap. Rather, a goal to attain a balanced ratio of ethnicities in order to provide a more stimulating social environment.

It’s important to remember that the discontinuity between the SAT/ACT scores required for Asian/White applicants and those for other URM students is not racism or some vendetta against those two groups. Rather, top Universities want to see their students excel to the maximum given their own personal situation. Usually, particularly Asian but also white students are subject to a lot more support, tutoring and mentoring than those from other ethnic groups. Obviously, it’s a bit of a shotgun approach to use ethnicity over, for example, socioeconomic circumstance, but it’s definitely a general indicator that can be helpful.

When you’re looking for the most interesting students who’ll excel the best in the same environment, it’s therefore not overly helpful to compare absolute performance from tests that are heavily preparation influenced. Rather, taking the top students from each pool (as there’s not a true capability difference between ethnicities) should serve to more or less find a true top set of students, who, given the incredible opportunities at a HYPSM school etc. will excel to similar levels.

The above is a reiteration of something an ex-admissions officer once told me.