Currency of ETF doesn’t really matter (except for currency hedged indexes), what matters is the currency of underlying stocks. Actually even more important is currency of their revenues/earnings, as that’s what ultimately determines the stock price too. And too bad for you that the swiss economy is so small: biggest swiss company (Nestle) is not at all swiss when you look at its financials, only ~2% domestic sales so lets be honest SMI is a dollar index.