The snowball theory of college superiority on wall-street

Assumptions: 1) People like to hire individuals from the school they attended 2) Firms will not allow their classes to become completely saturated by a single school 3) firms grow

Let's say that the person responsible for hiring went to Harvard. They are going to favor people from Harvard (I know all people will probably favor Harvard but let's say this person favors them more). They hire that person and that person eventually has a say in the hiring process and hires more Harvard people. Eventually, the firm becomes too saturated with Harvard students and makes an effort to diversify its class. They hire a person from yale who eventually has a say in the hiring process and favors yale students. And so on.

Possible outcomes would be that the firm reaches an equilibrium where the odds of acceptance from different schools steadies or it falls into a cycle where certain schools' odds grow quickly and then level off or even fall and then others grow quickly.

I think the reality is somewhere in the middle. The first firm I worked at disproportionally hired people from UVA 5 years or so before I started, so most of my bosses were from there. My class and the subsequent 2 classes I was there to see still had higher levels of UVA kids than you would expect at a somewhat good firm, but schools like Columbia and NYU were starting to grow quickly and occupy more spots. 

Also, I will say that the second assumption could be argued against and is pretty key to my thoughts above.