More than a dozen top U.S. colleges including Yale, Columbia and MIT have been sued for allegedly conspiring to manipulate the admissions system to hold down financial aid for students and benefit wealthy applicants.

The proposed antitrust class action lawsuit, filed Sunday in federal court in Chicago, accuses the university "cartel" of a long-running scheme to collectively adopt "a common formula for determining an applicant’s ability to pay" tuition, rather than competing freely over financial aid by trying to attract students through more generous aid offers.

At the same time, more than half of the schools have given preferential treatment to wealthy applicants by tilting the scales to favor the children of "past or potential future donors" and "through a largely secretive practice known as ‘enrollment management,’” according to the complaint.