The terrorist attack on New York on 11 September 2001 caused considerable disruption to the US economy, and especially to the US financial markets. The initial reaction of the financial markets was to increase the discount factor on future profits and reduce future profit projections, and hence stock market valuations fell markedly, as can be seen from charts 1 and 2. This fall has been largely reversed since the attack, but markets have in general continued their decline from their peaks a year or so ago. Falls have been particularly precipitate since July 2001, with the German and French stock market indices falling by 20 per cent over the last three months, whilst the Canadian markets have fallen even more. Stock market falls of the scale we have seen since July are almost bound to impact on the level of economic activity in the major economies. They are likely to reduce the rate of growth of the world economy over the medium term as well as change the structure of saving and investment.