Who is Behind the Occupy Movement?

Google this and you'll get a variety of answers:

The Unions
Anarchists
Communists
George Soros
Stephane Hessel
No-one (i.e. It started as a grassroots movement)

The answer I would be least inclined to believe is the latter. Unless the Arab Spring was also a grassroots movement. Which it wasn't.
Its a confusing matter. What do you call a cross between a Paradigm shift, and a dialectical synthesis?