1., According to folklorists, there is no written evidence for a "Friday the 13th" superstition before the 19th century.
2., Thomas W. Lawson's novel Friday, "the Thirteenth" in which an unscrupulous broker takes advantage of the superstition to create a Wall Street panic on a Friday the 13th is the reason given by most scholars as the reason for the current popularity of Friday the 13th.
3., Friday has been considered an unlucky day at least since the 14th century's The Canterbury Tales.
4., Professions have regarded Friday as an unlucky day to undertake journeys or begin new projects.
5., Friday is also the day when Jesus Christ was crucified, according to the Gospels, making it through folklore and adding to its unpopularity.
6., The connection between the Friday the 13th superstition and the Knights Templar was popularized in Dan Brown's 2003 novel The Da Vinci Code and in John J. Robinson's 1989 work Born in Blood: The Lost Secrets of Freemasonry.
7., Frigga being the name of the Norse goddess for whom "Friday" is named in English and triskaidekaphobia meaning fear of the number thirteen.
8., In Spanish-speaking countries, instead of Friday, Tuesday the 13th (martes trece) is considered a day of bad luck.
9., The Greeks also consider Tuesday (and especially the 13th) an unlucky day.
10., According to the Stress Management Center and Phobia Institute in Asheville, North Carolina, an estimated 17 to 21 million people in the United States are affected by a fear of this day making it the most feared day and date in history.
11., The longest period that can occur without a Friday the 13th is fourteen months.
12., Tupac Shakur died on Friday the 13th September 1996.
13., If you bought the S&P index on Thursday the 12th and sold on close of Friday the 13th every year since 1985 you would have made 339% on your money.