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why would they want to push it down later?

Manipulators make money on both sides of the markets they're manipulating.

See Aaron Russo's movie "Trading Places" for a humorous take on this reality, starring Eddie Murphy, Dan Aykroyd, and Jamie Lee Curtis: http://www.imdb.com/title/tt0086465/

Oh, cool, Thanks for the recommendation. I like movies like that!

You're welcome, enjoy!