They are just part of the market. You are not going to win or lose just because of a flipper. I am not talking about the dolphin..
they place huge orders on the bid and offer. they pull their orders and put it on the other side. eg. huge order to sell 2000 bund on the offer. people sell because of the herd mentality. the guy pulls the 2000 offer and puts 2000 on the bid. the people who sold say "*****". they screw with day traders and spreaders (cos they can flip 2 markets at once if they work as a team). they can affect long term traders who use charts as they manipulate the market through levels - thereby triggering auto stops and stopping people out for their own profit. it can be a very profitable strategy. the most well known is Paul Rotter, a czech who does 180,000 round turns a day on average allegedly, and makes (again allegedly) a few mill a week.
Thank Mr B for the only human respond!!! Do they have risk by doing so? If flipping is so good, then should Goldman or Morgan Stanley also join this game?
It's not risk free! If the position moves against them then they lose a lot. I have a buddy who's a STIR market maker at an investment bank. If a client places a big order in an OTC product, then he might hit the bid/ask in the bund to hedge off his risk. If there's 2,000 on the bid/ask then he might take the lot. And a bit of the next level as well. Doing that against a flipper would give them a big position that they don't want.