The dramatic fall in equity prices on most of the world's stock markets last October brought to the fore a number of questions on the markets' structure and functioning. Studies are under way in several centres which aim to explore the causes of the crash, the way that different markets-in particular the futures and options markets and the cash markets-reacted with one another, and the way that different groups of investors behaved. Some of these studies have already been published and include recommendations for changes to present arrangements. Others are still in preparation. This article does not attempt a detailed analysis of the crash, nor does it present specific policy recommendations, but it draws out features that are of interest and importance. The first part of the article describes the events of the crash in the London, New York and Tokyo markets; the second part examines some structural issues highlighted by the crash.