This paper uses a disaggregated approach to study the volatility of common stocks at the market, industry, and firm … levels. Over the period 1962-97 there has been a noticeable increase in firm-level volatility relative to market volatility …, while the number of stocks needed to achieve a given level of diversification has increased. All the volatility measures …

This paper studies three different measures of monthly stock market volatility: the time-series volatility of daily … market returns within the month; the cross-sectional volatility or 'dispersion' of daily returns on industry portfolios …, within the month. Over the period 1962-97 there has been a noticeable increase in firm-level volatility relative to market …