assistance to credit suisse required the utmost flexibility from the snb. as lender of last resort, it initially provided credit suisse with classic liquidity assistance ( ela ). based on an emergency ordinance by the federal council, it also provided an additional liquidity assistance loan ( ela + ). the statutory basis for this facility made it possible for loans granted under ela + to be secured solely by means of preferential rights in bankruptcy proceedings. ultimately the snb granted a further loan guaranteed by the federal government's public liquidity backstop ( plb ). thanks to ela +, it was possible to create the time window required for finding a comprehensive solution during the phase of high and exceptionally rapid outflows at 1 / 3 bis - central bankers'speeches credit suisse. without ela + credit suisse would have been in jeopardy of being unable to meet its financial obligations before the announcement of the acquisition by ubs, entailing substantial risks for financial stability. however, even after the acquisition had been announced, the snb's liquidity assistance remained crucial for credit suisse and ubs. there are statutory limits on the snb's room for manoeuvre in the area of financial stability. further tasks that are also important for the stability of the financial system fall under the responsibility of different authorities. for example, the snb is not responsible for the supervision of banks, and it has no legal basis to take over or resolve a bank. similarly, the snb cannot guarantee customer deposits at banks or provide banks with unsecured liquidity, i. e. without sufficient collateral cover a€ “ also not in the case of an acute crisis that poses a threat to global financial stability. the statutory framework for the snb's tasks and instruments is clear, and so too is the division of roles between the authorities. for the snb, its role as lender of last resort is of the utmost importance. neither in the case of the crisis at credit suisse nor in preceding crises was there ever a situation in which the snb would not have provided emergency liquidity assistance if this had been requested by a bank or if necessary to safeguard financial stability. the snb works continuously on being able to optimally perform its tasks as lender of last resort at any time. this includes testing its own emergency operations, as well as maintaining good contacts with other key central banks, relationships that are particularly valuable when it comes to

of the year. for over a year, this monetary policy divergence has been a major factor behind the depreciation of the euro against the us dollar. as chart 2 shows, since mid - 2014, the european currency has declined some 18 % in value and has also weakened on a trade - weighted basis, by around 9 %. the trade - weighted us dollar, by contrast, has gained approximately 15 % in this period. another important issue on financial markets has been the increased uncertainty due to the unresolved debt problem in greece. despite the fact that risk attitudes, as such, are positive, demand for safe investments and thus for the swiss franc has remained particularly strong. consequently, recent movements in the swiss franc have been influenced not only by the divergence between the dollar and euro regions, but also by persistent safe haven flows. the discontinuation of the minimum exchange rate led to a very substantial but short - lived appreciation in the swiss franc. the extent of this appreciation is shown in chart 3. the extreme movements in the exchange rate were accompanied by a sharp increase in volatility on the swiss franc foreign exchange market. since then, swiss franc volatility has declined, although it remains high in a long - term comparison with the period prior to the financial crisis. bis central bankers ’ speeches at the same time, bid - ask spreads, i. e. differences between the best purchasing and selling offers, widened substantially following the end of the minimum exchange rate. these, too, have declined in the past few months, although the bid - ask spreads remain relatively large. in trade - weighted terms, the swiss franc is no longer at the extreme levels that prevailed immediately after the discontinuation of the minimum exchange rate. however, it is still some 12 % above the level at the beginning of the year. thus, the swiss franc is still substantially overvalued. implementation and impact of negative interest exactly six months ago, on 18 december 2014, the swiss national bank ( snb ) decided to impose negative interest on sight deposit account balances at the snb for the first time, setting the rate at – 0. 25 %. when it discontinued the minimum exchange rate, it lowered the rate once again by 0. 5 percentage points, to – 0. 75 %. by imposing negative interest on sight deposits, the snb intends to move the three - month libor into negative territory and significantly reduce interest rates