Apparently people are struggling to make money in foreign exchange markets this year – as I heard for the thousandth time earlier this week! Mean reversion is playing a role, without doubt, but there is something, more basic, at the heart of participants’ struggles and one person’s experience from Brexit night is illustrative. How can it be that people have missed out on making money on a well-signalled, prolonged move in FX markets? Here is one possible answer – and it goes back to the roots of trading methodology