Say I make a 10 million trade on EUR/USD. Can a trade that big move the market, or is the market so big noone would even notice? How about 100 million?
I doubt you could ever make such a trade but 100mio on a Sunday night open would certainly have an impact although if you asked someone to make you a price on that you would have a very wide spread. All other times you might see some noise, depending on who was working the order and the time of day.
Is there something you�re not telling us?
It also depends on the currency. A $100 million transaction on EUR/USD would probably have little impact compared to say more illiquid currencies like Algerian Dinars or Austria Schillings.