Market-Hours and Institutions

I want to know if I am right at this.

During a specific open market-hours such as in NY, banks and institutions in the US can buy and sell currencies as normal. When the market is closed they, in the US, cannot buy and sell currencies at all. That is why the USD pairs volume is low when NY is closed and exchanges occur only between Sydney, Tokyo, and London.

funnyboy, welcome to FF!

Any institution can buy/sell any currency at any time they feel like it. There are no restrictions on times when they may trade. Many larger organizations have offices in different time zones such as NY, Tokyo, and London. This permits them to roll their positions to the branch that is currently open during business hours. This is why some people refer to currency positions that "follow the sun."