Does binding early admissions violate antitrust laws?

The DOJ seems to be looking into early decision in college admissions. Inside Higher Ed has the story, which makes it sound as if the investigation is focused on whether colleges (still) announce their early-decision admissions to their competitors, who then refrain from admitting those students.

Justice Department Investigates Early-Decision Admissions

"The Justice Department has started an investigation into whether some colleges' early-decision admissions programs violate federal antitrust laws through agreements among institutions or through the sharing of information about accepted applicants.
...
"The Justice Department letter does not detail what agreement or practices are being investigated. But the letter gives some indication, by outlining the documents that colleges are being required to maintain. These are:

"Agreements, both formal and informal, to exchange or otherwise disclose the identities of accepted students with persons at other colleges or universities.
Communications with persons at other colleges or universities relating to the transmission of identities of accepted students, including the justifications for such transmission.
Internal documents relating to the transmission of identities of accepted students to or from persons at other colleges or universities.
Communications in which identities of accepted students are sent to or received from persons at other colleges or universities.
Communications with persons at any other college or university relating to any student accepted at the college or university.
Records of actions taken or decisions made based in whole or part on information received from another college or university about the identities of accepted students.
Admissions records of any individual identified in any transmission as accepted by another college or university, including applications from, internal analyses of, and communications with the applicant."