Once every four years, most of the planet turns its attention to the soccer pitch for an unrivaled sporting pageant: the World Cup. And while Motley Fool co-founder David Gardner is not a superfan when it comes to futbol, he's a lover of sport in general, so it should come as little surprise that he, like billions of people around the globe, has his mind on the competition. But, at the Fool, our ongoing competition is to help you beat the market, so whatever he's doing, he's liable at some point to try to imagine it through an investor's lens.

In this segment, he considers the nature of sports and investing in a universe where our information is always incomplete. In other words, there's stuff you don't know, and it's going to lead to surprising outcomes. Underdogs will escape defeat. Seemingly well-run companies will be hiding fraud and corruption. Long-shot bets will be on the money, and pay off huge. But if you don't know what you don't know, how can you adjust your strategy to compensate? Gardner explains.

A full transcript follows the video.

This video was recorded on June 20, 2018.

David Gardner: Observation No. 5: there are surprises in the World Cup. That's part of the reason a lot of sports fans enjoy sports. I don't think it's just an American phenomenon, I suspect it's a global phenomenon, but since I've spent most of my time in this country, I know that in America, we love to root for the underdog. Again, I bet we're not the only ones who are this way.

It seems like, when Iceland is going to be facing off against Argentina -- as happened some days ago -- and Iceland had literally never been in the World Cup before, and Argentina has won some of them and was in the finals of the last one in 2014, how much fun is it to think that a country, a nation of 300,000 -- which is the population of Iceland today, about two-thirds of them just living in the capital city, living in the greater Reykjavik area -- 300,000 people, and their soccer team in there for their first World Cup, and they tied! This is not a spoiler, this happened a few days ago, so you should already know. They tied Argentina! That's a remarkable surprise. I'm not a sports betting man particularly, so I don't know what the odds of that were, but I suspect those were long odds and a big surprise.

Now, how does that apply specifically to invest in? Well, it can cut both ways. You can have good surprises and bad surprises. Briefly, let's start bad first. You should always be prepared to hear that something's gone wrong with one of your companies. We're all human, there are lots of errors. Sometimes, it might be some bad thing that's happened out there in one of the company's stores, and the CEO didn't even know about it. Sometimes, there's corruption in the office of the chief executive. All of these things have happened in business past to public companies. I've owned some of those stocks, too. I owned some Enron in one of my kid's portfolios at the time. That investment didn't do very well. We should always be prepared to be surprised badly by something that might happen with one of our companies.

So, of course, don't load up too much on any one thing. That's why we spread our bets. You can certainly overweight yourself, or allow great stocks, like some of the ones we're talking about this week, to become outsized portions of your portfolio. But just realize that there could be really bad news announced tomorrow. That's why we at The Motley Fool suggest you should not be on margin over-borrowing and loading up more than you have into the stock market, and you shouldn't be loading too much on any one stock, because bad surprises -- Argentina, Don't Cry For Me, Argentina -- bad surprises -- Leo Messi -- can happen. They will and do. The World Cup puts it on display for the whole world to see. And it's good for the world to be reminded that surprises happen.

Surprises can be fun, too. Some of the best surprises I've ever gotten come from stocks that have way outperformed my expectations. When we initially purchased amazon.com, when it was Earth's biggest bookseller, we certainly could not have foreseen all of the product categories Amazon would eventually enter. We didn't even know what a cloud was back then -- Amazon Web Services. We couldn't have imagined that there would be something called Amazon Prime, or that it would give you access, for free, to lots of stuff like videos that Amazon is paying to make part of its service for Amazon Prime members, or maybe get discounts at Whole Foods.

I assure you, in 1997, when we bought amazon.com at $3.21, we did not imagine any of that could happen. And yet, all of that has happened and more, and the stock has so far exceeded any expectations any of us could have had that all I can say is, no one was a genius to call it, but you and I could be geniuses just to buy it and to add to it and to hold it, and out-hold Wall Street trading in and out of these kinds of companies. You and I can hold them over the course of our lives and do wonderfully. So, positive surprises, too. Surprise. It's there in the World Cup, you have to love it.

John Mackey, CEO of Whole Foods Market, an Amazon subsidiary, is a member of The Motley Fool's board of directors. David Gardner owns shares of Amazon. The Motley Fool owns shares of and recommends Amazon. The Motley Fool has a disclosure policy.