What is Compound Interest?

In the vast expanse of financial wisdom, there’s a principle so profound that even Albert Einstein reportedly dubbed it the “eighth wonder of the world.”

It’s the magical force that allows money to grow upon itself, the secret sauce behind many fortunes: Compound interest. While there are myriad factors contributing to this phenomenon, the power of compound interest stands tall among them. Compound interest is the interest you earn on interest.

I’m a math guy – always have been. When I was younger, I often played with the calculator. What happens if you double your money every ten years? What about every one year? Every hour? Every second?

Those are obviously ridiculous assumptions, but I was fascinated by how quickly the numbers got really big. So when I was older, I looked at more realistic assumptions, like compounding at 5% per year (fixed income), 10% per year (equities), and 15% per year (alternative investments).

These are still round numbers, but through these exercises at a relatively young age, I began to master asset allocation.

Compound Interest Makes The Wealthy Get More Wealthy

It’s often said that the rich keep getting richer. While many factors contribute to this truism, the power and pull of compound interest cannot be understated. Whether you’re a budding investor or someone seasoned in the financial arena, understanding and leveraging compound interest can be the difference between moderate gains and monumental growth.

I cannot state this clearly enough: EVERY person who got rich through hard work and investing skill understands the power of compound interest. So it makes sense that as we launch into this financial series, it’s the very first thing you should understand, too.

Note: This is my second blog post of ten over the next ten weeks or so, in my current series called “Advanced Financial Insights For The Entrepreneur.”

What qualifies me to write this series? After getting my MBA in Finance in 1997, I worked for several top-tier investment banks over the next 15 years. These included stints of increasing responsibilities at Goldman Sachs, Bank of America, Citigroup, and JP Morgan.

Additionally, I am the founder of Sugarloaf Capital Group, a hedge fund with advanced quantitative strategies for wealthy families.

I have fairly deep knowledge and experience in all of the blog topics in this current series. Let’s dive in and learning about compounding!

compound interest

The Rich and Compound Interest

Wealthy individuals have long understood and leveraged the power of compound interest. Here’s how:

  1. Long-Term Vision: One of the primary drivers of compound interest is time. The longer money is invested, the more significant the compounding effect. Many affluent individuals start investing early and maintain a long-term perspective, allowing their wealth to snowball over the years, and even over generations.
  2. Reinvestment Strategy: Instead of withdrawing the profits or interest earned from an investment, the wealthy almost always reinvest. This continuous reinvestment amplifies the compounding effect.
  3. Diversified Portfolios: By diversifying their investments across various assets—stocks, bonds, real estate—the rich ensure that multiple streams of their wealth are compounding simultaneously.

Let’s dive into each of these concepts more deeply:

Long-Term Vision

In this fast-moving world, it’s easy to get caught up in the here and now, chasing quick wins instead of thinking about the bigger picture. But that’s where the true magic of having a long-term vision comes in. It’s like a steady anchor, keeping us stable when life throws its curveballs. By looking beyond today’s rush, we stay grounded, even in the wildest storms.

This vision isn’t just about dreaming of tomorrow; it’s about making choices right now that match our deepest goals. When our decisions are guided by long-term plans, they become more intentional, less about reacting to the moment and more about shaping our future. It’s all about thinking ahead, making choices that will pay off in the long run.

OK, enough with the generalities. Let’s look and some real examples that illustrate just how powerful compound interest can be.

Example 1: The Early Bird vs. The Late Starter

Meet Jane and John.

  • Jane starts saving when she’s 25. She invests $50,000 annually at a 7% annual return for 10 years. By the time she’s 35, she’s contributed a total of $500,000.
  • John, on the other hand, only starts saving at 35. He invests the same amount ($50,000 annually at a 7% annual return) but continues till he’s 65, contributing for a total of 30 years or $1,500,000.

By age 65:

  • Jane, despite only investing for 10 years, will have approximately $6,639,980 thanks to the compound interest accrued over the 40 years.
  • John, who started 10 years later but invested thrice as much as Jane, will have approximately $6,020,700.

Starting early gave Jane a significant advantage even though she invested far less overall. Get out your calculators and spreadsheets and run these numbers yourself! You will be astonished how quickly the numbers grow for those who invest early.

Example 2: Small Contributions, Big Results

Consider Lisa and Mark.

  • Lisa begins investing at 20, depositing $2,000 per month (a total of $24,000 annually) with an average annual return of 6%. She continues this until she’s 30, at which point she stops contributing but leaves her money to grow.
  • Mark starts at 30, depositing the same amount ($2,000 per month or $24,000 annually) with the same return of 6% and continues until he’s 60.

By the age of 60:

  • Lisa, who invested for only 10 years, will have a fund worth approximately $4,024,920.
  • Mark, even though he contributed for 30 years, will have a fund worth around $3,722,200.

Lisa’s early start, combined with the power of compound interest, outpaces Mark’s longer contribution period.

Example 3: Consistent Long-Term Investment

Let’s look at Alex and Sam.

  • Alex begins investing $30,000 annually from age 25 with a 7% annual return. He continues this till he’s 65.
  • Sam starts at the same age but only invests $10,000 annually, tripling his contribution to $30,000 annually from age 40 onwards till he’s 65.

By retirement at 65:

  • Alex, with consistent contributions, will amass around $8,180,000.
  • Sam, despite eventually matching Alex’s annual contributions, will gather about $5,910,000.

Consistent, early, and long-term contributions have a pronounced impact on the wealth accumulated over time. These examples amplify the unparalleled power of compound interest, especially when embraced early. The exponential growth over time can lead to vast fortunes.

The principle remains clear: When it comes to compound interest, time is truly of the essence. The sooner the start, the greater the potential rewards. I’ve got lots of spreadsheets available with simple compounding examples – leave a message in the comments if you’d lke to get access to them!

Reinvestment Strategy

Reinvestment is a powerful tool in the arsenal of any investor or entrepreneur, representing the choice to plow profits or dividends back into a business or investment, rather than extracting them.

A reinvestment strategy is about more than just putting money back into a venture; it’s about leveraging returns for exponential growth. We just covered how important the long-term is to compounding. Now let’s discuss what you should actually do during that long-term to maximize wealth.

The Core Tenets of a Reinvestment Strategy:

Capitalizing on Compound Growth

Reinvestment is the essence of compound growth. When you reinvest dividends or profits, they too begin to generate returns. Over time, this leads to growth that is geometric rather than linear. Essentially, you’re not just earning returns on your original investment, but also on the returns of that investment.

    • Example: The Retirement Saver – Emma

Emma begins her career at age 25 and decides to allocate $300 monthly into a retirement fund that offers an average annual return of 7%. By the time she’s 35, she’s saved $36,000 of her own money. If she were to stop investing at this point but let her money grow, by the age of 65, her investment would grow to approximately $332,000, even though she only contributed for 10 years.

Now, let’s consider if she continued her monthly contributions until she’s 65. By then, she’d have contributed $144,000 of her own money, but thanks to the power of compound interest, her investment would be worth around $883,000.

In this case, the compound growth on both her principal and the interest already earned plays a massive role in the end sum. Emma’s foresight in early and consistent investing allows her to capitalize fully on compound growth.

Accelerated Growth

Reinvesting profits can allow businesses to grow at a faster rate. This could mean expanding operations, investing in research and development, or entering new markets. Each of these actions can lead to increased revenues, and in turn, higher profits.

    • Example: The Tech Startup – Nimbus Tech

Nimbus Tech, a fledgling tech startup, initially saw a modest profit after its first year in business. Rather than distribute these profits among its stakeholders or store it away, the company chose to reinvest it into research and development for a new software product they believed had significant market potential.

This reinvestment led to the creation of a pioneering software tool that was rapidly adopted by businesses globally. As a result, Nimbus Tech’s revenue in the subsequent year tripled.

Had the company chosen not to reinvest its initial profits, it might have missed the window of opportunity to innovate and capture a large market segment. The reinvestment accelerated its growth trajectory significantly.

Mitigating Risks

By reinvesting, you’re essentially diversifying the use of your returns. Whether it’s spreading investments across a diverse portfolio or funneling profits into different sectors of a business, reinvestment can act as a hedge against potential losses.

      • Example: Real Estate Investor – Diego
        Diego has always been keen on real estate investment. After a few successful years in the market, he accumulated a substantial profit from a property sale. Instead of pouring all the profits into another high-value property, Diego chose to diversify.

He reinvested the gains into multiple avenues: a portion went into buying a smaller rental property, another into real estate investment trusts (REITs), and the final portion into renovating an existing property to boost its rental income.

By diversifying his reinvestments, Diego spread out potential risks. When an unexpected economic downturn affected the rental market, his income from the REITs (which remained stable) compensated for the dip in rental income.

Furthermore, the renovated property attracted long-term tenants, providing a steady cash flow. Diego’s strategy to reinvest and diversify shielded him from potential pitfalls, mitigating the overall risk to his investment portfolio.

financial advisors 6

Diversified Portfolios

You guys have probably heard this before, but it’s something I cannot emphasize enough. In the unpredictable realm of investing, diversification stands as a beacon of wisdom. Having a diversified portfolio means not putting all your eggs in one basket, but rather, spreading your investments across various assets or asset classes to reduce risk and potential volatility.

There is detailed mathematical analysis over 50 years of researhc that proves that diversification provides increased returns while reducing overall risk. It’s the holy grail of investing.

I won’t cover the math here (perhaps in a future post, I will), but trust me, it’s an absolute necessity if you are looking to grow your existing wealth.

A diversified portfolio can provide the safety net of stability during market downturns, and also position an investor to capitalize on different sectors or instruments as they rise.

The Rationale Behind Diversification:

  1. Risk Reduction: Different investments react differently to global events, economic shifts, or sector-specific changes. By diversifying, you ensure that a negative performance in one sector or asset class might be offset by positive performance in another.
  2. Potential for Higher Returns: Diversification allows investors to position themselves to take advantage of sectors or asset classes that are performing well, without being overly exposed to them.
  3. Capital Preservation: For many investors, especially those nearing retirement, capital preservation is as important as capital appreciation. A diversified portfolio, by minimizing the impact of any one poor-performing investment, helps in preserving the invested capital.

Examples of Diversified Portfolios:

Let’s dive into some examples here. I’ll keep the math simple and surface level to prove the point without losing anybody in the weeds.

Example 1: The Young Professional – Mia

Mia, a 28-year-old professional, wants to start investing her savings. She’s inclined to invest in tech stocks, given the tech industry’s booming performance. However, after consultation with a financial advisor, she decides to diversify her $10,000 savings as follows:

  • 40% in tech stocks, tapping into her initial inclination.
  • 30% in government bonds, offering stable and less risky returns.
  • 20% in real estate through REITs, to diversify into property without directly owning one.
  • 10% in international equity, giving her exposure to global markets.

A few years down the line, the tech sector experiences a slowdown, but her international equities perform well, and her bonds provide steady, albeit modest, returns. The impact of the tech sector’s decline is cushioned by her diversified investments.

Example 2: The Retiree – Robert

Robert, a 65-year-old retiree, has a substantial nest egg that he wants to invest. While he’s interested in capital appreciation, he also values capital preservation. Thus, he chooses a diversified approach:

  • 50% in blue-chip stocks, known for their stability and consistent dividends.
  • 25% in bonds, providing regular interest income.
  • 15% in precious metals like gold, a hedge against inflation and market instability.
  • 10% in growth-oriented mutual funds, allowing some exposure to higher risk-reward assets.

In a year where economic uncertainties lead to stock market volatility, Robert’s bonds and precious metals offer stability, ensuring his portfolio doesn’t suffer significant declines.

A diversified portfolio serves as a multifaceted tool, catering to both the cautious and the adventurous sides of an investor. It’s a blend of safety and potential, stability and growth. While it doesn’t promise immunity from losses, it significantly reduces the impact of any single underperforming investment.

For those navigating the dynamic waves of the investment world, diversification is akin to a well-balanced ship – designed not just to weather the storms, but to sail smoothly through diverse waters. And if you want to have and keep a job in the investment industry, diversification had better be one of the first words out of your mouth!


I’ve spent more time crunching numbers in my financial career than doing anything else. It’s fascinating to see the possibilities of what could happen in diversified financial portfolios.

Compound interest is often termed the ‘silent workhorse’ of the investment world. It operates quietly in the background but has the potential to generate remarkable results.

For the wealthy, it’s not just about having substantial amounts to invest; it’s also about understanding and leveraging tools like compound interest to maximize wealth growth.

In the words of Warren Buffett, “My wealth has come from a combination of living in America, some lucky genes, and compound interest.” If one of the world’s wealthiest individuals places such emphasis on it, perhaps it’s time we all took a closer look at this financial marvel.

Remember, in the realm of compound interest, time is your most valuable asset. Start early, be consistent, and watch the wonders of compounding unfold.

Verified by MonsterInsights