We study high-frequency exchange rate movements over the sample 1993-2006. We document that the (Swiss) franc, euro, Japanese yen and the pound tend to appreciate against the U.S. dollar when (a) S&P has negative returns; (b) U.S. bond prices increase; and (c) when currency markets become more volatile. In these situations, the franc appreciates also against the other currencies, while the pound depreciates. These safe haven properties of the franc are visible for different time granularities (from a few hours to several days), during both "ordinary days" and crisis episodes and show some non-linear features.