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Very usefull article of former interbank dealer Sean Lee
which give us deep insight of behaviour of big sharks.
We must learn this if we swiming in same sea with them.
Example of an interbank dealer who is looking at his order book and sees stop-loss orders to sell 200 million xxx/yyy at rates below 1.3700 down to 1.3690. The current rate is 1.3730 say. He has some options:
1. He can do nothing. He waits until the market breaks below 1.3700 and then he starts selling. The danger with taking this course of action is that other dealers have similar order boards and the market gets fast below the level. The customers might be filled 10 pips or more below their stipulated level and they would not be happy. Plus the dealer doesn't earn anything from this.
2. He sells 20 at 1.3730. The market starts drifting lower so he sells another 20 (if the market goes up he cuts the 20 short position for a small loss). He may buy 10 back but keep himself 20 or 30 short. Lets say his average entry rate for the 30 short is at 1.3730. When the market breaks below 1.3710, he sells another 30 and then he sells 100 at 1.3700 to ensure that the market trades at a rate below 1.3700. Then he sells the balance of the orders. He will have sold 200 xxx/yyy at an average rate of 1.3706 say. He will fill the stop-loss sell orders on average at 1.3696, with each customer being filled at their stipulated level. The dealer will have ensured that the customers cannot complain about slippage and at the same time he'll have earned $200,000. All dealers will follow the second course of action which in essence means that all stops are targeted. There is sometimes a downside risk in that the dealer may sell 100 xxx/yyy but the market suddenly stalls at 1.3700 due to a barrier or a big Sovereign or corporate buyer. If this happens the dealer must act very quickly to start covering his shorts before the market races higher.