Dubbed the ‘greatest humourist the United States has produced’, Samuel Langhorne Clemens, known better by his pen name Mark Twain, is probably best known for the characters of Tom Sawyer and Huckleberry Finn.

For investors though, it’s one of Twain’s lesser-known creations, Pudd’nhead Wilson, the much-maligned star of his own novel in 1894, that will take centre stage as we enter the month of October. Spawning what is now dubbed the Mark Twain Effect, the titular character gives his view on the month, when investing, in one of his more infamous speeches:

“October. This is one of the peculiarly dangerous months to speculate in stocks. The others are July, January, September, April, November, May, March, June, December, August, and February."

Looking back at October performance over the years

Although Twain’s views on the stock market are meant to be sarcastic, they do in fact have a ring of truth to them. Since the beginning of the 20th century, plenty of market cycles have seen a dip in performance during the tenth month of the year. Famously incorporating Halloween, a period traditionally known for its scares already, October has frequently spooked investors over the decades.

The term could have gained traction after the great Banking Panic of 1907, an event that led to multiple bank-runs and heavy selling at the US stock exchange. All that prevented a serious financial crash was the work of a banking consortium to provide major funding to New York itself, during what was a notoriously cold October in the Big Apple.

The Stock Market Crash that led to the US Great Depression of 1929, a financial disaster on an unparalleled scale, began on 24 October, better known as ‘Black Thursday’ with the market losing 11% of its value in frantic trading. Black Tuesday occurred the following week, seeing a loss of over 23% in just two days.

In more recent times, the black days of October have continued, with Black Monday in 1987. During 16 October, all markets closed in London due to adverse weather, after they re-opened, the speed of the crash accelerated. By midday, the UK Blue Chip Index had dropped by 14% and a further 11% the following day, some of the largest losses on record. Domestic stocks then continued to fall, albeit at a less precipitous rate, reaching a trough in mid-November at 36% below their pre-crash peak, not recovering until 1989.

Investors have witnessed some extreme market events

Although October has had its fair share of market mishaps over the years, it’s interesting to note that the month has historically heralded the end of more bear markets than the beginning. In fact, October gets a poor rap when considering that most investors have probably lived through a range of highly volatile months. The fact of the matter is that terrible market events do not all cluster in one particular month, if they did, perversely, it would make an investor’s job that much easier.

Take the Global Financial Crash of 2008, after months of market turmoil throughout the summer, Lehmann Brothers filed for bankruptcy during September. The collapse of Silicon Valley Bank and Credit Suisse during the Spring of last year all led to investor angst during other parts of the year. Even the Covid-19 pandemic that rocked financial markets, causing unprecedented market volatility and central bank measures, did not really manifest in the West until March 2020.

Maybe it’s Mark Twain’s fault, maybe it’s just investor psychology, but October, despite hosting Halloween, should be no scarier for investors than any other month of the year.

Perhaps it’s just a difference in lexicon between the British and our American cousins. After all, anyone from North America will tell you with glee that October hails the start of the Fall - just not necessarily for financial markets.

Of course, despite volatility and extreme market events, investing over the long term remains a tried-and-tested route for investors and good outcomes.

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The value of investments can go down as well as up and your clients could get back less than they paid in.

The views expressed in this blog should not be regarded as financial advice.