If you take the Dollar exchange rate from the time the stock was bought and the Dollar exchange rate from the time it was sold, you get 3000 Dollars. In Euros the gain was just 300. (We bought the stock in Euros while in Germany let's say for 10,000 Euros, sold it there for 10,300 Euros, so we gained 300 Euros. Then we immediately reinvested 10,300 Euros in Germany in Euros.). So the Dollar gain is just a theoretical one - due to the exchange rate! As we never transferred the money to the US to profit from the exchange rate gain, we never realized it. But we still have to pay taxes in the US for 3000 theoretical Dollars! Isn't that terrible?