A very old saying with a very modern problem: Exploring behavioural biases

"Sell in May and go away, come back on St. Leger's Day" originated in an era long before Bloomberg terminals, ETFs or global capital flows. London's financial class would leave the city for the summer social season, thinning market liquidity and often suppressing returns. History gives us echoes rather than templates, but it is striking how many such sayings persist long after the conditions that created them have faded. And yet, investors still reference it. Why? Because it taps into a deep behavioural instinct to identify a simple rule that removes uncertainty. If only the calendar ...