From The Free Forex Encyclopedia
Banking institutions cater to both the majority of commercial turnover and large amounts of speculative trading every day. The set of forex products offered by various banking institutions vary depending on their size. Some banks offer only spot exchange and currency forwards while the larger institutions offer currency options, currency swaps, currency futures, and option-dated currency forwards.
A large bank could trade billions of dollars daily, much of which is undertaken on behalf of customers, but some is conducted by proprietary desks, in other words: trading for the bank's own account.
A study by Greenwich Associates reveals that the top foreign exchange dealers are dominated by banking institutions such as Deutsche Bank, UBS, Citigroup, Barclays, and the Royal Bank of Scotland. The exact percentage of the daily global forex turnover accountable to banking institutions is not known but Deutsche Bank and UBS each comprise more than 10% of the market share. What’s for certain is that a sizeable part of daily forex trading is concentrated among the world’s top 10 foreign exchange banks. Around 90% of all foreign currency transactions are done by banks, companies, and individual traders.