Cynically, I would say that their overall number of applications was perhaps a bit soft and they need to up those numbers so they can show a higher reject % in May.
hear you @45 Percenter but the alternative explanations don't make a lot of sense....they wanted to make the holidays less stressful for applicants? i'm sure that good people work in their admissions office but I find it hard to believe that this goodwill would be generated now. On the other hand, this is my first journey through college admissions and perhaps extending the deadline is not unusual... on the same day UPenn announced this, Vanderbilt also pushed their deadlines to January 5.... I'll admit, though, that it's tough for me not to see a strategy of more applications built into this....
The extension was obviously intended to goose the numbers. The Penn Admission's office was well aware of its winter vacation many many months ago. The last minute decision to extend the deadline was based on the last minute news regarding applicant numbers. If they were soft, the Admission's office only strategy was to pump demand any way they can -- which meant extending the deadline. U Chicago and Dartmouth did the same thing. My sympathies lie with all of the earnest applicants who sacrificed their time over the past month or two to get their applications submitted on time and play by the rules.