I can't find the article now, but a large trader recently got charged with spoofing the futures market. What the heck is spoofing?
Placing orders without the intention of ever being filled in order to make the order book look a certain way.
Do some research, you'll find it. I'm not sure of the name of the document. Topic has been discussed on et before in regard to the recent nav ordeal.
It is considered market manipulation. Regulators are very focused on this abuse right now in both the futures and securities markets.