These cover the bulk of countries outside Europe. Forex brokers catering for India, Hong Kong, Qatar etc are likely to have regulation in one of the above, rather than every country they support. Some brands are regulated across the globe (one is even regulated in 5 continents). Some bodies issue licenses, and others have a register of legal firms.
Traders at the banks would collaborate in online chat rooms. One trader would agree to build a huge position in a currency, then unload it at 4 p.m. London Time each day. That's when the WM/Reuters fix price is set. That price is based on all the trades taking place in one minute. By selling a currency during that minute, the trader could lower the fix price. That's the price used to calculate benchmarks in mutual funds. Traders at the other banks would also profit because they knew what the fix price would be.
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