What concept does 'exists' instantiate?

Maverick has a great post here. If 'some horse exists' says that the concept horse is instantiated, what concept does 'something exists' instantiate? (I have simplified his argument somewhat, without missing its force, I hope).

Actually this is all too difficult for a Saturday afternoon, so instead here is Happy Go Lively by Laurie Johnson, who also wrote the Avengers theme music. Happy Go Lively to me sounds identical to Holiday for Strings by David Rose, who also wrote The Stripper.

I first went to the States in 1971, when inside absolutely every lift and in every shopping mall they played music like Holiday for Strings. To the teenager I was then, Jimi Hendrix represented all that was true, and shopping mall music everything that was horrible. I don't know if they are playing Hendrix in shopping malls, but music has moved on since then, in some sense of 'moved on'. For example, here is Bring Me The Horizon playing something completely horrid at the Reading Festival last year. The singer has so many tattoos it seems he is infected by gangrene.