Swiss National Bank

The Swiss National Bank (SNB) sets monetary policy for the Swiss franc. Because the franc is a magnet for safe-haven money, the SNB has spent years trying to stop it soaring, using negative rates and buying huge amounts of foreign currency.

Its most infamous moment came on 15 January 2015. Without warning, it scrapped the 1.20 floor it had held under EUR/CHF since 2011. The franc rocketed, at one point by around 30% in minutes. Some brokers went bust, and many traders' accounts were wiped out. It remains the textbook case of why stops are not guaranteed in a gap.