despite some remaining volatility and fragility. against this background, it is necessary, from a monetary policy point of view, not to postpone the exit from non - standard measures for too long, in particular since we always emphasized it would be a state - contingent process. before i discuss the challenges of the phasing - out in more detail, let me briefly recall some key aspects of our monetary policy implementation. in the euro area, the bulk of liquidity is provided via revolving refinancing operations ( collateralized lending ) of different maturities, with the main refinancing operation, that is the one week operation, being the most important. prior to october 2008, refinancing operations were conducted as variable rate tenders, with allotment amounts closely aligned with the aggregate liquidity needs of the banking system ( often referred to as “ benchmark allotment ” ). conceptually, the liquidity needs of the banking system mainly result from non - banks ’ demand for banknotes and substantial remunerated reserve requirements. the particular tender procedure means that average short - term money market rates are normally just slightly above the minimum bid rate in the weekly main refinancing operation, which serves as the key policy rate. however, in october 2008, the variable rate tender procedure with benchmark allotment was replaced by a fixed rate full - allotment procedure, in order to ensure banks ’ liquidity despite the drying up of the interbank money market following the lehman collapse. the full allotment policy allowed banks to accumulate substantial amounts of surplus liquidity ( or excess reserves to use u. s. terminology ), which could be lent to other banks or placed in the eurosystem ’ s deposit facility – an overnight facility to deposit excess reserves. as a result, short - term money market rates usually traded only a couple of basis points above the eurosystem deposit rate throughout most of 2009 and 2010. this was by design. meanwhile, given an ongoing normalization in financial markets, money market rates have increased significantly but smoothly without any monetary policy tightening signals and the corresponding headlines. despite the overall improvements in financial market and money market conditions, some financial institutions, however, continue to rely strongly on the liquidity support measures provided by the eurosystem. in principle, the strong demand for central bank liquidity from these eurosystem counterparties could lead to elevated tender spreads after the return to a variable rate tender procedure.

as an invoicing currency in increased by around half a percentage point and five percentage points, respectively. with non - eu countries, however, trade invoicing patterns remained relatively stable. the trading volume in global foreign exchange markets rose to almost 4 trillion usd in april 2010 as compared to 3. 3 trillion usd in april 2007. in fact the euro proved to be recognized as a safe haven currency. in a recent study the ecb found that the best predictor of a safe haven status is not the interest rate spread, as assumed in the carry trade literature, but rather the net foreign asset position, the country risk and external vulnerability. this confirms that macroeconomic fundamentals of the issuing country are an important determinant of “ safe haven ” currencies. bis central bankers ’ speeches sovereign debt crisis : the greek challenge although the talks of a crisis of the euro are misguided, there is no reason for any complacency. we are still in challenging times. especially in greece, the situation is fragile. athens has made remarkable progress in consolidating its public finances. its population has to experience cuts, which are unprecedented in the post war european history. nevertheless, an additional financial aid package was necessary including additional fiscal consolidation and privatization efforts. in this context, euro area heads of state and government reaffirmed their commitment to ensure the financial stability of the euro area last thursday. bold and important decisions were taken, which include : euro area heads of state and government announced 159 billion euros of new financial support for greece that will consist of 109 billion euros from the euro area and the imf. financial institutions will contribute 50 billion euros after agreeing to a series of bond exchanges and buybacks that will reduce greece ’ s debt burden. the interest rate on the loans will be reduced and maturities will be extended to up to 30 years with a 10 - year grace period. these amended conditions will also be available for portugal and ireland. the european financial stability facility ( efsf ) will be more flexible – an amendment the ecb has suggested for quite a while. the efsf will be empowered to buy debt across stressed euro countries on the secondary market. the fund can also aid troubled banks and offer credit - lines to countries that are not under a program to repel speculators. euro area governments will guarantee any greek debt offered as collateral during money market operations in case a temporary credit event might be triggered. that will enable greek banks to keep ref