In this case it is the huge size of orders and the spoofing (orders never intended to be around long or filled on either the sell or buy side, false fake orders) to influence & manipulate market pricing with smaller buys down below trying to get filled. This is not only ommoral which no one in the market cares about but illegal attempt/intent to price manipulate. And yes the big boys do this all the time with their much more sophisticated HFT algos.

I don't buy for a second this one little guy caused the flash crash but he certainly contributed anymore than the Goldeman Sachs trader they tapped for the CDS debackle. Not sure why after all these years the CFTC decided to act after the SEC blaming that Mutual fund and got away with it in their 100 page report of BS, somehting certainly seems odd about timing and the fact the two agencies have different accounts of events & causation.

Of course they continue to ignore the gold/silver market spoofing and illegal market manipulations and these markets are for sure a layup. They have already made a couple fines and there will be more likely but the real easy target is the Crimex and the bullion banks HFT algos and stop hunts, spoofing, large concentrated short positions.