> I don't think I understand how currency trading works. If you owned EUR the value of the EUR only changed relative to the CHF. If you owned CHF you gained 15%

> I don't think I understand how currency trading works. If you owned EUR the value of the EUR only changed relative to the CHF. If you owned CHF you gained 15% against all currencies. > How do people lose money on this? Are people somehow trading on the CHF/EUR exchange rate? And is so, why? The CHF was pegged to the EUR. When you currency trade you go long one side of a currency pair and short the other. So you borrow 40000 Euro and buy Franc or vice versa. There is always a specific currency pair involved. The usual reasons to take a position in a pegged currency is either to bet that the peg breaks (which people being long Euro obviously didn't do), or to extract value from a difference in interest rates (the carry trade, I don't know if that applied but there must have been something attractive about shorting CHF....)