Chart of the Week: One cheer for Christmas

‘Twas the night before Christmas, when all through the house

Investors awaited the pre-Christmas bounce.

Theory aside, the literature was clear,

For those with investments ’tis the ‘most wonderful time of the year’.

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Investors are well aware that much money can be made on stock markets in the pre-Christmas bounce. Indeed, there is now a wealth of academic research on the matter, which offers a conclusion about as close to unanimous as economists are ever likely to reach: “Equity markets do better in the week before Christmas than in other weeks”. Probably.

But the occurrence of such a phenomenon year-in and year-out is a challenge to the economic orthodoxy, which insists that there are no dollar bills left lying on the sidewalk. In fact, some research suggests that pre-holiday returns may be as much as 10-20 times greater than they are during the rest of the year. Additionally, it turns out that this is not just about Christmas either. Something similar tends to occur around other major holidays too, although returns before religious holidays exceed those of non-religious ones, possibly because they tend to be associated with more time off work.

So what is going on? A long list of theories that attempt to answer the question have fallen by the wayside, but an enduring (if unconfirmed) hypothesis is that it is a result of a psychological increase in euphoria associated with festive periods; in other words, ‘Christmas cheer’. This would also explain why the effect is predominately seen in countries that actually celebrate Christmas.

However, the additional Christmas bonus appears to be in decline. The moving average of the difference between festive and non-festive returns has fallen sharply in recent years and is close to its lowest ever level. Without knowing why this phenomenon has occurred in the past, it is difficult to say with any degree of confidence why it may be fading now. But the dramatic increases in algorithmic trading may be playing the role of ‘Scrooge’ and spoiling the party.

Based on ‘Christmas economics – a sleigh ride’, Birg & Goeddeke (2014).

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