This article is from Darkstar at Forex Factory

The Structure of Forex Brokers 

There has been much discussion of late regarding broker spreads and liquidity. Many assumptions are being made about why spreads are widened during news time that are built on an incomplete knowledge of the architecture of the forex market in general. The purpose of this article is to dissect the market and hopefully shed some light on the situation so that a more rational and productive discussion can be undertaken by the Forex Factory members.
 
We will begin with an explanation of the purpose of the Forex market and how it is utilized by its primary participants, expand into the structure and operation of the market, and conclude with the implications of this information for speculators. With that having been said, let us begin.
 
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EDIT: I have received numerous requests for readers to share this information on other forums. I have no problem with anyone doing so provided they include the following statement prior to posting the content:
 
“Originally posted by Darkstar at Forex Factory.”
 
Sending me a courtesy PM with a link to the thread would be much appreciated as well.
Last edited by Isotonic, Mar 26, 2007 4:15pm Reason: change to web font
Unlike the various bond and equity markets, the Forex market is not generally utilized as an investment medium. While speculation has a critical role in its proper function, the lion’s share of Forex transactions are done as a function of international business. 
 
The guy who buys a shiny new Eclipse more than likely will pay for it with US Dollars. Unfortunately Mitsubishi’s factory workers in Japan need to get their paychecks denominated in Yen, so at some point a conversion needs to be made. When one considers that companies like Exxon, Boeing, Sony, Dell, Honda, and thousands of other international businesses move nearly every dollar, real, yen, rubble, pound, and euro they make in a foreign country through the Forex market, it isn’t hard to understand how insignificant the speculative presence is; even in a $2tril per day market.
 
By and large, businesses don’t much care about the intricacies of exchange rates, they just want to make and sell their products. As a central repository of a company’s money, it was only natural that the banks would be the facilitators of these transactions. In the old days it was easy enough for a bank to call a foreign bank (or a foreign branch of ones own bank) and swap the stockpiles of currency each had accumulated from their many customers.
 
Just as any business would, the banks bought the foreign currency at one rate and marked it up before selling it to the customer. With that the foreign exchange spread was born. This was (and still is) a reasonable cost of doing business. Mitsubishi can pay its customers and the banks make a nice little profit for the hassle and risks associated with moving around the currency.
 
As a byproduct of transacting all this business, bank traders developed the ability to speculate on the future of currency rates. Utilizing a better understanding of the market, a bank could quote a business a spread on the current rate but hold off hedging until a better one came along. This process allowed the banks to expand their net income dramatically. The unfortunate consequence was that liquidity was redistributed in a way that made certain transactions impossible to complete.
 
It was for this reason and this reason alone that the market was eventually opened up to non-bank participants. The banks wanted more orders in the market so that a) they could profit from the less experienced participants, and b) the less experienced participants could provide a better liquidity distribution for execution of international business hedge orders. Initially only megacap hedge funds (such as Soros’s and others) were permitted, but it has since grown to include the retail brokerages and ECNs.