The credit crunch of 2007-08 was the third phase of a larger and longer financial crisis. The first phase was the emerging market defaults of the 1990s. The second was the new economy boom and bust at the turn of the century. The third was the collapse of markets for structured debt products, which had grown so rapidly in the five years up to 2007.

The manifestation of the problem in each phase was different – first emerging markets, then stock markets, then debt. But the mechanics were essentially the same. Financial institutions identified a genuine economic change – the assimilation of some poor countries into the global economy, the opportunities offered to business by new information technology, and the development of opportunities to manage risk and maturity mismatch more effectively through markets. Competition to sell products led to wild exaggeration of the pace and scope of these trends. The resulting herd enthusiasm led to mispricing – particularly in asset markets, which yielded large, and largely illusory, profits, of which a substantial fraction was paid to employees.

Eventually, at the end of each phase, reality impinged. The activities that once seemed so profitable – funding the financial systems of emerging economies, promoting start-up internet businesses, trading in structured debt products – turned out, in fact, to have been a source of losses. Lenders had to make write-offs, most of the new economy stocks proved valueless and many structured products became unmarketable. Governments, and particularly the US government, reacted on each occasion by pumping money into the financial system in the hope of staving off wider collapse, with some degree of success. At the end of each phase, regulators and financial institutions declared that lessons had been learnt. While measures were implemented which, if they had been introduced five years earlier, might have prevented the most recent crisis from taking the particular form it did, these responses addressed the particular problem that had just occurred, rather than the underlying generic problems of skewed incentives and dysfunctional institutional structures.