The M7.
It’s the informal super elite group of seven private business schools generally considered to have the world's best MBA programs. If you’re in business, you know their names: Harvard, Stanford, Wharton, Kellogg, Booth, Columbia, and MIT Sloan.
https://poetsandquants.com/2015/01/05/the-m7-the-super-elite-business-schools-by-the-numbers/