This particular topic is so important that I decided to revisit it again. The discussion below adds further refinements and creates an even stronger tie to behavioral finance (i.e. how emotions affect investment decisions).  Additionally, for those of you who desire more in-depth coverage of the math and statistics presented, I have included that at the very end of this article.  Let’s delve deeper into this topic and what is meant by “reality”.

The first key to successful stock investing has more to do with your emotions than a fundamental understanding of what causes stocks to move up or down. Emotions about money can be a powerful thing and cause people to behave in irrational ways.  One of the most common phrases passed on to investors as a piece of wisdom is to “buy low and sell high”.  However, study after study has shown that most individual investors fail to heed that advice.  Why does this happen?  Well, I would submit the real cause is behavioral and based upon incomplete information.

Most individual investors are told when they start investing in stocks via mutual funds and/or ETFs to expect an annual return of 8% to 9% per year. You will find that many financial calculators to help you plan for retirement on the Internet have that as one of the inputs to calculate the growth of your portfolio over time.  While that information is not too far off the mark based upon historical returns of the S&P 500 stock index, the actual annual returns of stocks do not cooperate to the constant frustration and consternation of so many investors.

That brings us to the first key to successful stock investing:  The actual yearly returns of stocks very rarely equal the average expected.  The most common term for this phenomenon is referred to as volatility.  Stocks tend to bounce around quite a bit from year to year.  Volatility combines with the natural instinct of people to extrapolate from the recent past, and investing becomes a very difficult task.  I will get deeper into the numbers at the very end of the post for those readers who like to more fully understand the concepts I discuss.  I do need talk in general about annual stock returns at this point to expand upon the first key.

Below I have provided a chart of the annual returns of the S&P 500 index for every year in the 21^st century:

What is the first thing you notice when looking at the yearly returns in the table? First, you might notice that they really jump around a lot.  More importantly, none of the years has a return that is between 8% and 9%.  The closest year is 2004 with a return of 10.9%.  If the only piece of information you have is to expect the historical average over time, the lack of consistency can be extraordinarily frustrating and scary.  In fact, individual investors (and sometimes professional investors too) commonly look back at the last couple of years and expect those actual returns to continue into the future.  Therein lies the problem.  Investors tend to be gleeful when returns have been really good and very fearful when returns have been very low.  Since the average never comes around very often, investors will forget what returns to expect over the long run and will “buy high and sell low”.  It is common to sell stocks after a prolonged downturn and wait until it is “safe” to buy stocks again which is how the sound advice gets turned around.

I will not get too heavy into math and statistics, but I wanted to provide you will some useful information to at least be prepared when you venture out to invest by yourself or by using a financial professional. I looked back at all the returns of the S&P 500 index since 1928 (note the index had lesser numbers of stocks in the past until 1957).  The actual annual return of the index was between 7% and 11% only 5 out of the 88 years or 5.7%.  That statistic means that your annual return in stocks will be around the average once every 17 years.  The 50-year average annual return for the S&P 500 index (1966-2015) was approximately 9.8%.  Actual returns were negative 24 out of 88 years (27.9% of the time) and greater than 15% 42 out of 88 years (48.8% of the time).  How does relate to the first key of stock investing that I mentioned earlier (“The actual yearly returns of stocks very rarely equal the average expected”)?

Well, it should be much easier to see at this point. If you are investing in stocks to achieve the average return quoted in so many sources of 8% to 9%, it is definitely a long-term proposition and can be a bumpy ride.  The average return works out in the end, but you need to have a solid plan, either by yourself or with the guidance financial professional, to ensure that you stick to the long-term financial plan to reach the financial goals that you have set.  Knowing beforehand should greatly assist you in controlling your emotions.  I recommend trying to anticipate what you do when the actual return you achieve by investing in stocks is well below or quite high above the average in your portfolio.  Having this information provides a much better way to truly understand and your risk tolerance when it comes to deciding what percentage of your monies to allocate to stocks in my opinion.

When you look back at the performance returns for stocks, it makes more sense why investors do what they do from the standpoint of behavioral finance. That is how emotions affect (all too often negatively) investment decisions.  If an individual investor is told at the outset that he or she can expect returns of 8% or 9% per year, the actual annual returns of stocks can be quite troubling.  Having that information only leads to a general disadvantage.  When stock returns are negative and nowhere near the average, individual investors tend to panic and sell stocks.  When stock returns are quite higher than the average, individual investors tend to be more euphoric and buy even more stocks.  This affect is magnified when there are a number of consecutive years with one of those two trends.  If stock returns are essentially unchanged, most individual investors become disengaged and really do not even see the point of investing in stocks at all.

I believe it is extremely important to know upfront that stocks are likely to hit the average return once every 17 years. That statistic alone is a real shocker!  It lets individual investors truly see how “unusual” the average return really is.  Plus, there is a better explanation for fear and greed.  Stock market returns will be negative once every 4 years.  Keep in mind this does not even include stock returns that are below the average yet still positive.  Lastly, every other year the stock market returns will be above the average (in my case I was measuring above the average with the definition of that being a stock market return greater than 11%).  It is no wonder why individual investors get greedy when it looks like investing in the stock market is so easy after seeing such great returns.  Conversely, the occurrence of negative returns is so regular that it is only natural for individual investors to panic.  Since the average only comes around approximately once every two decades, that is why confusion abounds and investors abandon their long-term financial plans.

I will readily admit sticking to a long-term financial plan is not easy to do in practice during powerful bull or bear markets, but I think it helps to know upfront what actual stock returns look like and prepare yourself emotionally in additional to the intellectual side of investing.  Now I always mention that statistics can be misleading, conveniently picked to make a point, or not indicative of the future.  Nevertheless, I have tried to present the information fairly and in general terms.

Additional Information on Stock Market Returns (Discussion of Math and Statistics):

Please note that this information may be skipped by individual investors that are scared off by math in general or have no desire to dive deeper into the minutiae. One of the first things to be aware of is what expected returns for stocks are.  An expected return is what the most likely outcome would be in any particular year.  Expected returns provide misleading results when there is a high degree of variability in the entire dataset.  In the case of stock market returns, there is an incredible amount of variability.  The industry term for variability, which is the statistical term, is volatility.  Due to the fact that the expected return almost never happens, it would be wise for the financial services industry to truly and better define volatility.  Most individual investors do not know that there is far more of a range of possible outcomes for stock market returns.  Individual investors associate hearing average returns with some volatility from Financial Advisors or financial media in the same way as the classic “bell curve”.  As discussed in further detail above, the outcomes do not even come close to approximating the “bell curve”.

One important thing to be aware of when it comes to actual performance returns of an individual’s investment portfolio is that average/expected values are not very important. In fact, they really lead to a distorted way of looking at investing.  Average/expected values are based on arithmetic returns, where the overall growth in one’s investment portfolio is tied to geometric returns.  The concept of geometric returns is overlooked or not fully explained to individual investors.  Here is the perfect example of how it comes into play.  Let’s say you own one share of a $100 stock.  It goes down 50% in the first year and then up 50% in the second year.  How much money do you have at the end of the second year?  You have the original $100, right?

Not even close. You end up with $75.  Why?  At the end of the first year, your stock is worth $50 ($100 + $100*-50%) after decreasing 50%.  Since you begin the second year with only that $50, that is why you end up having $75 ($50 + $50 * 50%).  The average annual return is 0% ((-50% + 50%) divided by 2)) for the two-year period.  Whereas your geometric return is negative 13.4%.  Essentially that number shows what happened to the value of your portfolio over the entire timeframe and incorporates the ending value.  Think of it as having $100 + $100 * -13.4% or $86.60 at the end of year one and then $86.60 + $86.60 * -13.4%) or $75.  Note that you never actually have $86.60 as the portfolio’s value at any time, but the geometric return tells you how much money you actually earned (or lost) over the entire period and how much money you end up with, otherwise known as the terminal value of your portfolio.  The geometric return will ALWAYS differ from the arithmetic return when a negative return is introduced as one of the outcomes.  As an individual investor, your primary concern is the terminal value of your portfolio.  That is the dollar value you see on your brokerage statement and is the actual amount of money you have.

Financial professionals forget to focus on geometric returns or even bring them up to clients. This omission is important to individual investors because negative returns have an outsized effect on the terminal value of an investment portfolio.  For example, in the example above, it is quite clear that losing 50% and then gaining 50% do not “cancel each other out”.  The negative percent weighs down the final value of the portfolio.  That is why it is extremely important to use the geometric return of the portfolio.  This result is due to the fact that the compounding of interest is not linear.  It is a geometric equation which is why the geometric mean comes into play.  Without going fully into the explanation of those equations, the main takeaway for investors when it comes to annual returns is that negative returns have more of an effect than positive returns.

Taken together, it is important to utilize the concept of multi-year geometric averages. Individual investors never want to simply add up the annual returns of a series of years and then divided by the number of years.  That result will overstate the amount of money in the investment portfolio at the end of the period.  The preferred approach is to use the geometric average which is referred to as the annualized average return.  That percentage is the number most relevant to investors.  Additionally, longer timeframes of these returns are best to look at given the extreme amount of volatility in yearly stock market returns.  It gives a better picture of how the stock market has moved.

When looking at the stock market returns for the S&P 500 index over five-year periods using the period 2001-2015, they yield surprising yet informative results. The five-year returns from 2001-2005, 2006-2010, and 2011-2015 were 0.54%, 2.30%, and 12.57%, respectively.  Valuable information comes from looking at extended periods of time using the same time increment.  The overall return during 2001-2015 was 5.01%.  The effect of these longer timeframes smooths the stock market return data, but even then the stock market returns vary quite a bit.  Note that the overall return from the entire historical period of the S&P 500 index is roughly 9.50%.  These three selected chunks show two periods of underperformance and one year of outperformance.  The reason stock market returns tend to hover around the historical average is due to the fact that these returns are tied to the overall growth the economy (most commonly Gross Domestic Product – GDP) and corporate profits.  In the meantime though, stock market returns can vary a lot from this expected return.  However, they are unlikely to do so for incredibly long periods of time.

By incorporating the understanding of volatility and geometric returns into your understanding of the “reality” of stock market returns, you will be able to better refine your own risk tolerance and how to craft your long-term financial plan. A better grasp of these concepts makes one far less likely to react emotionally to the market, either with too much fear or too much greed.