This can be seen in chart 5, which shows the example of interest rate differentials between Germany and Switzerland for three-month, two-year, five-year and ten-year maturities. While interest rates on the money and capital markets declined as a result of negative interest, mortgage rates did not decrease to the same extent. Indeed, for mortgages with longer terms, rates are slightly higher than they were at the beginning of the year. The main reason for this divergence is that a major part of bank refinancing costs consists of interest paid on savings deposits, which has not fallen below zero as did interest rates on the money market. Because interest on savings deposits is significantly higher than the money market interest rate, bank interest margins came under pressure after they had hedged the interest rate risk associated with their mortgage business, and some mortgage rates were increased. Fears that negative interest might contribute to a significant decline in mortgage rates and, in turn, to stronger growth in mortgage lending have so far proved unfounded. For investors, by contrast, the current low interest rate environment means that the challenges have increased. It is even more difficult for them to find yield-bearing investments. I should emphasise, however, that this investment predicament is an international phenomenon and not limited to the Swiss franc alone. Conclusion I will now come to my concluding remarks. Initial experience has shown that the interest rate instrument is also effective in negative territory.
This shows that marginal costs – the costs of an additional unit of Swiss franc liquidity – are relevant for transmission on the interbank market. Although trading activity on the money market remains lower than before the financial crisis, it has revived somewhat. For instance, turnover on the  2  BIS central bankers’ speeches  secured money market, in particular on the Swiss franc repo market, has risen since the introduction of negative interest. As intended, negative interest has been transmitted from the money market to the capital market. The lower interest rates for all maturities have widened the traditional interest rate differential against other countries again somewhat. Previously, they had narrowed substantially. On the money and capital markets, the interest rate differential is now greater than it was without negative interest, in particular for short-term interest rates. Chart 4 shows the path of interest rates for three-month loans on the Swiss franc and euro money markets, together with the differential. The greater interest rate differential helps to ensure that Swiss franc investments are less attractive than investments in euros and other currencies. Moreover, the rise in the interest rate differential has increased the cost of hedging foreign currency positions on the forward exchange market, which is an additional factor dampening Swiss franc demand. Although the interest rate differential has risen, it is still considerably below the long-term average, particularly since interest rates abroad decreased more substantially during the financial crisis than those in Switzerland.