For investments priced in EUR that invest in securities priced in USD, the presence of this additional currency risk mandates the use of a hedge if the indexes are going to track. (money.stackexchange.com)
The reason for this is that, long - term, the movement of securities prices is biased upward. (freemoneyfinance.com)
The essence of the argument can be described by the simple statement that security prices reflect all available information. (us.dimensional.com)