Trading U.S. instruments in an Euro based IB account

Am I right in my thinking that IB effects an immediate exchange of euros into the equivalent amount in dollars at the current exchange rate whenever a trade in a dollar based instrument is entered and then converts any profit or loss back into euros at the end of the trade in case you have an euro based account ?

And if so, how much does one lose in this exchange process back and forth, even if trade entry and exit takes place at the very same day ?

Thanks for letting me know.

.

There is no automatic exchange. You are borrowing USD. Interest rate charges are due if you keep positions overnight. Alternatively, you can buy USD on IDEAL or IDEALPRO.