alt Hacker News> Does the cost of material goods and services mostly stay the same in EUR, or does it somewhat follow the S&P?
I don't understand this question, are you asking if material goods and services in Europe, which uses EUR, "somewhat" follows the S&P, a US stock market index?
If you have to hold USD to buy and sell USD products (as a European) it doesn't make sense to compare your SPY position vs EURUSD because you have to use those USD to buy something or pay some debt.