The major difference between US and UK based brokers comes from the new NFA (National Futures Association) regulations that have been introduced this year. Those new regulations limit US brokers to use only the FIFO (first in, first out) method for the accounting of their clients, thus making hedging not possible. Most of the US based brokers provided hedging type of orders, so that when the new rule was first introduced, it caused great difficulties for those companies. The complications did not come only because most clients had got used to trading with hedge orders, but also because the trading software was made to operate this way. The situation made all those companies to either move to other countries, mostly in the UK, or create subsidiaries there. At the present moment there are not that many brokers left in the US and most of them also have subsidiaries in the UK, so in this sense you have the same brokers in both countries. The difference is that in UK there are many others as well and all companies based in the UK can have hedging type of orders. Moreover, the FSA has always been known for providing good regulation basis for trading with financial instruments. It also has fully implemented the MiFID directive, which is the basis for regulations in the European Union.