What is Risk?

Risk is a tricky concept to pin down in the investing world. There’s no good definition of what it truly is, or how people relate to it. And it’s – by far – the most important concept in finance.

The Challenge of Defining Risk

Finance isn’t alone in not being able to define key concepts, though – go ask a physicist to define time. They’ll probably say something about entropy, causality, or the arrow of time (which is the rough equivalent of saying, “Risk is risk because it’s risky”), but they don’t really have a good way of explaining what time is. These fundamental concepts that everyone just kind of “gets” are surprisingly difficult to explain precisely.

But it’s important to work through what risk means – both generally and specifically to you. The better we understand the concept, the better we’ll understand what risks the market will pay us to take on and how it will do so – and what that means for how you should invest.

Investment Risk

Most people think of risk in terms of the variance of their investments – how much they wiggle up and down on the performance charts. Variance, or, as it is more commonly shown, standard deviation – is a pretty good proxy for risk, especially of the short-term variety. But it’s not risk itself – just like an apple falling out of the tree isn’t gravity itself – and it even falls short as a proxy in many circumstances.

Here is an example. Let’s say that we have two investments: A and B.

• Investment A has an average return of 10 percent and a standard deviation of 15 percent.
• Investment B has an average return of -10 percent and a standard deviation of 0 percent.

From a pure standard deviation standpoint, investment A looks riskier. But from a broader, more practical viewpoint, investment B is clearly a greater risk. Investment A is much more likely to help you reach your investment goals than investment B. Investment B may be more predictable, but it’s increasing the risk of your total portfolio.

Others have tried to define risk in terms of a security’s expected return. They say the risk is the difference between the actual return and the expected return. This falls apart because it’s circular. A security’s expected return is defined by its exposure to (certain types of) risk, and then the risk is the chance that you won’t get your expected return.

Like standard deviation, this can be a useful way of thinking about risk, but it’s not risk itself.

I think the most appropriate (though still not quite right) way to think about risk is the chance that things won’t work out and you won’t be able to meet your objectives.

Going back to that standard deviation example, investment A has a positive expected return and could potentially help you get where you want to go, and investment B is the equivalent of throwing away money. This latter route is not going to help you reach your investment goals, no matter how flat its standard deviation promises to be.

A Personalized Approach to Managing Risk

If risk is the chance that things won’t work out, then it must be defined individually. How you experienced the tech crash, great recession, or recent bull market is unique. It’s different from how your friends, neighbors, and (probably) even your spouse experienced them.

If risk is defined individually, then it must be valued differently as well. This is where it gets interesting.

Since everyone values risk differently, we all demand different levels of expected return from different assets. You may be more nervous about small company risk than I am for some reason, so you wouldn’t be willing to pay as much for a share of a small company’s stock as I am. You demand a higher expected return if you’re going to invest in something that makes you as nervous as a small company.

Everyone puts in their two cents and trades on their idiosyncratic risk preferences. Then, the market does what it’s best at – incorporates loads of disparate information – and figures out the resulting prices (implicitly coming up with everything’s expected returns).

Your task is to figure out which risk factors with positive expected returns make sense to you (and in what amounts) based on how the market has priced them. The answer is going to be slightly (or not so slightly) different for everybody. It’s based on how you think about risk relative to the average market participant. In other words, your asset allocation should be based on how you are different from the average investor in the market.

Finding Your Comfort Zone

Let’s back up and look at how you might be different from the market. A quick note: I’ll be speaking in broad, sweeping, generalizations here. Your personal situation overrides everything, but I can’t speak to everyone’s unique circumstances in a blog post, so we’ll have to make do with a broad brush.

If you’re reading this, you are probably either in retirement or somewhere in the process of preparing for it, and maintaining your desired standard of living is your most important financial goal. For you, risk is defined as not being able to fund that standard of living in retirement. Anything that makes reaching or maintaining your goals more likely reduces your risk, and anything that makes this less likely increases your risk. Everything else is just details.

We may not be able to precisely define risk, but it's something we all recognize when we see it. And everyone sees it differently. What matters is how you deal with risk and how you are different from the average market participant. Your job is to understand your own risk preferences and tailor your investment strategy accordingly. There's no one-size-fits-all solution – it's about finding what works best for you.