In 2008 - 09 the world experienced the most severe financial and economic crisis since the Great Depression. The global financial crisis is attributed to a variety of factors, such as developments in the subprime mortgage sector, excessive leverage, lax financial regulation and supervision, and global macroeconomic imbalances. At a fundamental level, however, the crisis also reflects the effects of a long period of excessively loose monetary policy in the major advanced economies during the early part of this past decade. The global financial crisis has led to a new wave of thinking on all issues related to both monetary policy and financial regulation. The practice of both monetary policy and financial regulation had tended to become too formula bound and hence predictable. While these new principles are being debated, it is important to realize that in the face of unexpected developments that always arise in the financial sector, there is an important role for the exercise of judgment by both monetary authorities and financial regulators. Whereas considerable progress has been achieved on the principles governing this regulatory overhaul, very significant challenges remain on the implementation issues that will arise as a new regime takes hold globally.