Well, you are making quite a lot of assumptions here: - currency is very different from equities - while one could argue that a central bank deciding to peg it

Well, you are making quite a lot of assumptions here: - currency is very different from equities - while one could argue that a central bank deciding to peg it's currency to $ is a realistic scenario, it simply doesn't make sense for equities (an equity is basically a right for present and future earnings of a company - good luck 'perfectly' predicting that !) - as you note, there would still be speculators, since there is always uncertainty. There are numerous examples of countries pegging their currencies and then when unexpected happens... - traders / sales would still compete for order flow of the clients (and get the cut), so there would still be a game to be played albeit for smaller margins