Be afraid, be very afraid of today, Friday the 13th.

Just kidding.

But if you’re running a company, do you notice a loss of productivity, caused by one or more of the following changes? Your staff won’t travel or may be uncharacteristically cantankerous and uncooperative in that they refuse to tackle what they usually do routinely—sales calls, closing deals or meeting clients for lunch.

And why is your star salesperson wearing lots of amulets today and reeking of garlic?

Blame it on Friday the 13th.

The Stress Management Center and Phobia Institute estimates between $700 million and $800 million are lost every Friday the 13th because of people's refusal to travel, purchase major items or conduct business.

However, fear not, it’s only one day once in a blue moon.

But more importantly, the S&P’s 500 has generally performed well over the last 20 years on this most ominous of days.

The last Friday the 13th was in November 2009. On that day, the S&P gained 0.57 percent. In fact, the index has been higher on seven of the last eight Friday the 13ths. And the average change on those days has been up 0.34 percent, with positive returns 68 percent.

So take the phobia institute’s study with a grain of salt, or, as it were, a clove of garlic.

But to be safe, stay away from black cats, ladders and cracks in the sidewalk. And keep working.

So will you be making any major financial decisions today? Share your opinion below: