My Interpretation on the Ending.

American Psycho Ending- My Perception:

Okay, well basically all the murders were in his mind. He basically was in another mindset and wanted to kill some people enough that he made a reality for himself that only existed to only him. 

That's why everyone says Paul Allen is still alive and that apartment he went to was empty and people were looking to rent it. Kinda fucked up I know.

It seems the movie was supposed to be ambiguous, especially the ending, but the author who wrote the book said, in the book it's in his mind. I see it that way in the movie. But the end of movie seems to be open to interpretation.

I guess people would be baffled by the ending, and you know I think people are to a degree. I mean it seemed like maybe it happened or maybe it didn't. I guess you can interpret it in whatever way you want. Whatever you think happened isn't wrong if you have a reason or two to back up your own interpretation of the film.