Luis Puente

Luis Puente

Educator and District Leader

2711 LBJ Freeway Suite 300

Farmers Branch, TX 75234

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November 5, 2018

Understanding compounding in investments

Understanding compounding in investments

Successful investors like Warren Buffett didn’t just hit a home run on a stock pick.

Warren Buffett hit lots of home runs, but compounding turned those home runs into history-making investment achievements.

Compounding doesn’t have to be a big mystery. It just means that the annual increase is added to the previous year’s balance, which, on average, gives each year a larger base for the next year’s increase. The concept of compounding applies to any interest-bearing savings or investments or to average percentage gains.

Here’s a quick example:

Starting investment: $10,000 Interest rate: 7%

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The rule of 7 & 10
There’s a reason a 7 percent return was chosen for this example. You can see that the total interest return over 10 years is about double the original investment. This is an example of the “Rule of 7 & 10”, which says that money doubles in 10 years at 7 percent return and that it doubles in 7 years at 10 percent interest. It’s not an exact rule, but it’s close enough so you can quickly estimate without a spreadsheet or calculator.

The simple interest example above only begins to show the power of compounding. It doesn’t include any additional investments after year one. In investing, compounding can come from more places than one, particularly if the stocks you own pay dividends. (A dividend is a share of the profit that is distributed to shareholders.)

Compounding in investing
Investing in stocks or mutual funds may provide an average annual return in line with the simple interest example, assuming investments are well diversified to mimic the broad market performance. For example, the S&P 500 return over the past 10 years is just over 7 percent annualized.[i] When you adjust for dividends, the annualized return is close to 10 percent. If those numbers sound familiar – like the rule of 7 & 10 – it’s a coincidence, but the past 10 years of S&P returns are very close to historical averages. Knowing what we now know, it’s easy to figure out that $10,000 will double in 7 years, assuming that market performance is aligned with historical averages. In reality, market performance may be higher or lower than past averages – but over a longer time line, short term peaks and valleys usually blend into an overall trend in direction.

If you’re concerned that you don’t know as much about investing as Warren Buffett, don’t think you need to be an oracle to be a successful investor. Many times, the best stock to pick for individual investors may be no stock at all. There are a myriad of investment options from which to choose without buying stocks directly. Talk to your financial professional about what choices may be available for you.


[i] https://dqydj.com/sp-500-return-calculator/

This article is for informational purposes only and is not intended to promote any certain products, plans, or strategies for saving and/or investing that may be available to you. Market performance is based on many factors and cannot be predicted. Before investing or enacting a retirement strategy, seek the advice of a financial professional, accountant, and/or tax expert to discuss your options.