Benjamin Graham, Warren Buffett's teacher, used to warn that the person he called "Mr Market" is a neurotic: his moods fluctuate between incredible optimism and overwhelming depression. At present, he is moving from insouciance to anxiety and so from riskier assets towards cash or even that classic hedge - gold.

Mr Market has reason to be anxious. The contemporary combination of high to very high valuations of real assets (such as housing and equities), low spreads of risky assets over risk-free ones (such as emerging market and corporate bonds over US Treasuries), rising real prices of commodities (notably oil) and huge shifts in patterns of saving, investment and finance around the world (shown in the global "imbalances" and rising indebtedness of household sectors, notably in the US) is good reason for nervousness.