Swiss National Bank's Chair Thomas Jordan, in an article in Sunday's Schweiz am Sonntag (a Swiss newspaper) says the bank is ready to intervene if the FX market, if required:

"The franc is significantly overvalued and should therefore weaken over time. In addition, we have emphasized we will become active in foreign exchange markets if required"

Via Reuters.

Bloomberg adds:

"Whether we need to go lower with the negative rates depends on international developments

"At minus 0.75 percent we've already gone quite far and we're waiting to assess the effect"

He added that Europe and the U.S. have probably reached the lower bound of interest rates