The chief ‘weapons’ of a stock market correction are surprise, or fear and surprise, or …. (please carry on based on your familarity with Monty Python).

I should say that a logically predictable inflection point in the normal market cycle that can be anticipated is clearly not a surprise to the well informed (for example October 2021) but a ‘crash’, such as in October 1987 or the onset of the great financial crisis of 2008 will be unexpected by many market participants and that is the very reason that it progresses to become a severe valuation reset that may go on for as long a several years. In simple terms, there is panic.

‘The Impact of the Highly Improbable’ is a now legendary book by Nassim Taleb that formalised the Black Swan theory, essentially the idea that outlying events, or those deviating from common and current experience may have a disproportionate impact on perception and in consequence reactive behaviour.

The idea is not that black swans are unknown (apparently, they were known about by the Romans) but that in regions where white swans are seen daily in numbers, suddenly seeing a black swan comes as a shock and is almost never anticipated (because how could you?).