Possibly for this reason, markets are often more jittery than usual during the summer months. Last year, for example, it was in August that American share prices began their final protracted fall before a storming bull run that took them to new all-time highs. That may be down to liquidity, which, with many investors also off reclining in the sun, tends to be slightly thinner during the holiday season than in the rest of the year. It may also be that the lack of veterans on banks’ trading floors allows panic to set in more easily. Prices can swing a lot further before someone musters the courage to push back.