Short term and long term price elasticity of currencies If I have 1% of the world supply of US dollars, and I decide to sell all of them to buy Euros, how much should I expect the exchange rate to change? Is there some kind of empirically determined price elasticity of demand that I could use to predict this? I've tried looking this up but I haven't been able to find it.

I'm also interested in the long run price elasticity of demand. Eg, how much should I expect my 1% USD sale to affect the price of USD in a year?
There is no way to predict that.

A "price" is just the level of the last transaction. What happens in the next transaction does not depend on the previous transaction. So if you sell dollars at 1.10 dollars per Euro, the next person to sell dollars might sell them at 1.12 or 1.08 or some other amount based on a myriad of factors. There is no way to predict what trades might occur in the future, just from knowing the trade you made in the present.