Do initial margin requirements pertain to when you write a naked option, say the Euro, OTM. then the market moves to make it ITM, say by 50 points. When the buyer exercises, will you have to pay just the stated initial margin requirement or that plus the 50 points? I am asking this because with a stock, if it moves from 20 to 25, it costs more. If the euro moves from 1.2 to 1.21, it still costs the same. Thus, their shouldn't be unlimited risk to a naked option, just the 2835 initial margin.