Possible euro exits unsettling - and alluring - for market

NEW YORK (Reuters) - News that the world's top foreign exchange broker has been testing its trading system against a possible euro collapse conjures a host of images and ideas for currency traders and investors, not all of them bad.

If one or more country ditches the euro, the revival of old currencies would mean more opportunity for profit in the $4 trillion-a-day FX market, traders say.