In the latest bold decision by a central bank, Switzerland’s National Bank (SNB) announced earlier Thursday it is implementing negative interest rates.

In an effort to lower the value of its franc, SNB unveiled a rate of -0.25% on sight deposits on accounts with more than $9.77 million. “The new rate will be introduced on 22 January and will only affect banks and large companies who use the ‘sight account’ to transfer funds quickly and without restrictions,” reports the BBC.

Shares of the safe-haven CurrencyShares Swiss Franc Trust (NYSEArca: FXF) fell 0.8% in Wednesday trading and earlier hit its lowest levels in over four years. While there has been talk of the franc recently firming, FXF has tumbled 9.3% this year and 4.2% over the past 90 days. [Yen, Franc ETFs as Safe-Haven Plays]

Shares of the iShares MSCI Switzerland Capped ETF (NYSEArca: EWL), the largest Switzerland ETF, are higher by nearly 1% today. Although the franc has fallen this year, EWL has disappointed with a 2.2% loss. However, EWL has easily outpaced the comparable Germany, France and United Kingdom ETFs.

“Over the past few days, a number of factors have prompted increased demand for safe investments. The introduction of negative interest rates makes it less attractive to hold Swiss franc investments, and thereby supports the minimum exchange rate. The SNB is prepared to purchase foreign currency in unlimited quantities and to take further measures, if required,” said SNB in a statement.

SNB typically tries to implement a minimum exchange rate of 1.2 francs per euro and vowed to enforce that cap “with the utmost determination.”