> Does the cost of material goods and services mostly stay the same in EUR, or does it somewhat follow the S&P?

... Wait, why would you expect the price of goods to follow the valuation of, well, any market index, never mind one specific foreign market index? Like, I don't understand why you think that would happen. If anything, you'd expect a minor inverse relationship, at least on a global scale; rapid growth of cost of goods indicates inflation, which implies central bank tightening, which tends to depress stock values a bit.