Bears who reckon that overheated stocks are set for an autumn dip have market history on their side.
In America, investors have lost an average of almost 1% in every September since 1926. In each of the other 11 months, they gained almost 1%, says Brett Arends in The Wall Street Journal.
It's a similar story here, says Chris Dillow on Investorschronicle.co.uk. Since 1966 the All-Share index has returned 0.9% on average in September. And that's not just down to "a few awful months".
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Strip out the three worst Septembers and the month's average return is still 0.16%, worse than any other month bar June.
The big picture: the banks' debt binge
This chart from the Bank of England's Andrew Haldane is a stark illustration of the banking debt bubble, says Tim Price of PFP Wealth Management. It shows the results of a hypothetical bet, made in 1900, on banks outperforming non-bank sectors.
One hundred pounds was invested in banks and £100 in shorting the rest of the market. Until 1985, this would have returned 2% a year; by the end of 2006 the figure soars 16% before falling to under 3% in late 2008.
Banks boosted their return on equity, a key gauge of profitability, to spectacular levels by loading up on leverage, an effect that went into reverse when the bubble burst.
