Despite its unlucky reputation, there is no evidence to justify the superstition around Friday the 13th.
However that is not to say that it does not impact businesses - with some sectors suffering from a slump in trade on the cursed day.
Others, meanwhile, take steps to ensure they do not tempt fate (or put off customers).
The dark past
The superstition around the number 13 has a long history.
A story from Norse mythology has the trickster Loki arriving at a dinner of 12 other gods - making him the 13th guest. The dinner ended with the god of light, Baldr, being killed.
Similarly, Judas was believed to have been the 13th guest at Jesus' last supper.
The number 12 is also often seen as the 'right' or 'total' number - from hours on a watch, to months in a year, to cycles of the moon. As a result, the number above that has become undesirable to some.
Meanwhile Fridays have long had negative connotations of their own - from it being the day of Jesus' crucifixion through to it once being Britain's designated day for hanging criminals.
And so when the two negatives are combined, as happens at least once a year, the superstitious get particularly anxious.
Market misfortune
Some may point to the US stock market crash of Friday, 13th October 1989 as proof that the day is a bad one for business.
That saw the Dow Jones close nearly 7% lower on the news that a takeover bid for United Airlines’ parent company had collapsed.
But using that to justify the superstition would require ignoring the many stock market slumps and crashes that occurred before then and since - none of which fell on a Friday the 13th.
However there is some evidence that Friday the 13th does unusual things to stock markets.
A research paper published in 2019 suggested that the day tends to yield lower returns for traders than a 'normal' Friday.
Its impact on markets also appeared to extend beyond the 13th - with activity rising in the days before and after the feared date.
But this was not due to some unseen, unlucky force - but rather the superstitions of some investors who sought to avoid doing business on the day itself.
Meanwhile, a now 20-year-old study by the Stress Management Centre and Phobia Institute in North Carolina suggested that as much as $800m was lost to the US every Friday the 13th, as superstitious consumers avoided travel or put off major purchases.
Exactly how they came to that staggering sum is unclear - but even if it was accurate, it's likely that much of that spending is displaced to other days rather than wiped out completely.
The Paraskevidekatriaphobia Penalty
Still, some businesses here will feel the pinch today.
Ireland's Wedding Band Association says its members always see a dip in bookings on a Friday the 13th, as brides and grooms-to-be avoid tying the knot on the unlucky date.
Figures from one of Ireland’s main airports also suggest that fewer passengers than normal had travelled on recent Friday the 13ths - down roughly 4-5% on other Fridays.
But that may not tell the full story.
The Humanist Association of Ireland, for example, says its members see no discernible difference in the number of ceremonies performed on a Friday the 13th when compared to other Fridays.
That suggests that any reluctance to wed on a Friday the 13th tends to be confined to more religious couples.
Meanwhile, the last two unlucky days fell in January and October 2023. These are months that tend to be quieter for aviation in general, which could explain a quieter-than-usual airport.
For their part, most of Europe’s major airlines say that they see no dip in bookings on the day - suggesting there are not many passengers whom are too superstitious to take to the skies today.
But despite that the superstition is clearly a concern for some in aviation, with many companies taking steps to ensure would-be bookers are not put off.
Airlines including Ryanair, Lufthansa, KLM, SAS, Qatar, Swiss and Vueling all skip the 13th row on their planes, instead jumping from 12th to 14th.
A spokesperson for KLM said it did this because some passengers "may feel uncomfortable or anxious" about sitting in row 13, and may even refuse to do so altogether.
Swiss said it also skipped 13 due to it being considered unlucky in some countries, and pointed out that Geneva and Zurich airports don’t have a gate 13.
Lufthansa said its planes are also without a 17th row, as this number is considered unlucky in Italy and Brazil.
Others, particularly in Asia, skip the 4th row due to the negative connotations that number has in some countries.
A similar practice is common in the hospitality industry, with many hotels around the world lacking a 13th floor. Though it's a problem that only a handful of hotels on this island are tall enough to encounter.
When the Hastings Hotel Group converted Belfast city’s Windsor House office block into the Grand Central Hotel in 2018 it decided to skip the 13th floor due to the number's superstitious connotations.
However the 15 storey Metro Hotel in Ballymun, Dublin, has opted to retain the number.
Lucky for some
Of course there are plenty of businesses that have benefitted from Friday the 13th.
As on-the-nose as it may be, the Friday the 13th horror franchise has been extremely lucrative for Paramount Pictures, Warner Brothers and Victor Miller, the screenwriter credited with its creation.
The first film was released in 1980 (on a Friday, 9th of May, strangely enough) and, according to Box Office Mojo, it and its 11 follow-ons have taken a combined $908m at the US box office when adjusted for inflation.
That's more than other major horror series including Scream and Saw, and does not include the money made from related merchandise, spin-off TV shows or the numerous books, comics or video games.
Taylor Swift has also claimed 13 to be her lucky number.
She says this was due to the fact that she was born on the 13th of December, her 13th birthday fell on a Friday the 13th, and her first album reached 'gold' status 13 weeks after its release.
Last year she also released the concert film of her Eras Tour on Friday, 13th October.
Given that it was one of the (many) factors that pushed her into billionaire status, you can understand why she's so fond of the date.
