most direct /powerful effect is interest rate arbitrage

euro zone interest rate is already very very low - negative all the way to 3-5 year for creditworthy countries.

further QE will push up government funds price up even further and yield further down.

this will make USD denominated bonds even more attractive and pushes up USD relative to EURO.

the question is how much of this is priced in. we will know tomorrow.

i suspect buy on rumor and sell on news, as always.

just my 2c