Beyond TMT, we find no systematic increase in the importance of industry effects. Instead, we observe that the ratio of industry to country effects follows a U-shape pattern from the mid-1980s to the late-1990s, a cyclical pattern whereby global industry effects become temporarily more important in relative and absolute terms around periods of stock market distress, such as October 1987 and March 2000. We view this cyclical pattern as further evidence that the recent increase in industry effects is temporary
