Big news today in international finance:The story is that, since the Euro debt crisis kicked off in 2011, Europeans have flooded to buy Swiss francs as a stabler asset. Letting it rise without intervention would kill Swiss exports to the EU, which compose a significant portion of its economy. The Swiss National Bank, then, decided to buy as many Euros with Swiss Francs as it takes to not let the exchange rate get too high for the Franc.
The consequence: the SNB has an asset sheet with as many Euros as national GDP. This leaves them exposed to sudden depreciations in the Euro, and this was the cited reason for the move.
CHF/EUR exchange rate is still at a bit above parity, and investors are pissed. The Swiss stock exchange is down 8% today, and there's going to be panic for financial products denominated in Swiss Francs (like mortgages in Eastern Europe). What the Swiss Bank will try to do now is to lower interest rates to penalize holding of Swiss Francs. That won't stop others from blaming the Bank for destroying its credibility, and causing even more uncertainty in the Eurozone.