In another reminder of the impact of central banks in markets, CurrencyShares Swiss Franc Trust (NYSEArca: FXF) is down 18% in the year since the Swiss National Bank set a floor on the euro/franc exchange rate.

FT Alphaville notes the level will be one year old tomorrow.

In September 2011, the SNB said it would “no longer tolerate” a euro/franc exchange rate below 1.20. [Swiss Franc ETF in Focus After SNB Move]

Investors were flocking to the Swiss currency as a safe haven from Europe’s debt crisis. The central bank intervened to provide relief to Swiss exporters and the economy, and prevent deflation.

FXF is down 17.8% for the year ended Sept. 4, according to investment researcher Morningstar.

Earlier this year, the SNB warned it would step in to enforce the currency floor. [Swiss Franc ETF May Take Hit if SNB Intervenes Again]

FXF is designed to track the movement of the Swiss franc against the U.S. dollar. The currency ETF holds assets of $334.8 million.

CurrencyShares Swiss Franc Trust