As a retail trader you never get the chance to see how the dealers and the brokers work and take your orders. You are sitting on one side of the computer while these brokers and dealers are sitting on the other side and manipulating the orders in order to maximize their profits. Talk of efficient markets and best price discovery. You should read this Bloomberg article and get a glimpse of how the interbank market works. As a retail trader you need to have some understanding of how the interbank market works.
Now regulators from Bern to Washington are examining evidence first reported by Bloomberg News in June that a small group of senior traders at big banks had something else on their screens: details of each other’s client orders. Sharing that information may have helped dealers at firms, including JPMorgan Chase & Co. (JPM), Citigroup Inc. (C), UBS AG (UBSN) and Barclays Plc (BARC), manipulate prices to maximize their own profits, according to five people with knowledge of the probes. The foreign exchange is a huge market something like $5.3 trillion daily turnover. However it is also largely unregulated as it is over the counter and there is no fixed location which leads to manipulation by the big banks.