This paper examines the problems of estimating risk measures and their stability in thin markets. It shows analytically that conventional approaches used in previous studies can lead to serious overestimates of the stability of risk measures when shares are subject to thin trading. It then demonstrates, using UK data, that this is, in fact, a serious practical problem, and that the resultant biases are of precisely the form predicted. Finally, the paper presents reliable evidence on the stability of UK risk measures by using an estimation method designed to avoid thin trading bias. Using this approach, risk measures are found to be as stable in the UK as they are in the USA.

The consensus view of the influential economist John Maynard Keynes is that he was a stellar investor. We provide an extensive quantitative appraisal of his performance over a quarter century and present detailed analysis of his archived trading records. His top-down approach initially generated disappointing returns with no evidence of any market-timing ability. However, from the early 1930s his performance improved as he evolved into a bottom-up stock picker with substantial active risk and pronounced size and value tilts. Our reconstruction of Keynes’s stock trading provides a unique record of realized performance and sheds light on how equity investing developed historically.

A central measure of the efficiency of the Initial Public Offering (IPO) market is the extent to which issues are underpriced. We present new and comprehensive evidence covering British IPOs since World War I. During the period from 1917 to 1945, public offers were underpriced by an average of only 3.80%, as compared to 9.15% in the period from 1946 to 1986, and even more after the U.K. stock market was deregulated in 1986. The post‐WWII rise in underpricing cannot be attributed to changes in firm composition, and occurred in spite of improvements in regulation, disclosure, and the prestige of IPO underwriters.