Here's How Big a $50-Per-Week Investment in the S&P 500 Could Grow Over the Long Haul

Investing small amounts of money wasn't always practical in the past. Commission fees were a big deterrent, and they would incentivize investors to put a lot of money in at once to minimize their impact. Now with commission-free trading options, however, it's easier than ever for investors to make much smaller investments without worrying about fees. This can be ideal if you're able to cut out some weekly expenditures from your budget and instead put that money into the stock market.

While it can seem like it may be a painstaking process to invest at a rate of $50 per week, that's the equivalent of putting aside $200 per month, or around $2,600 over the course of a full year. In smaller pieces, it can be more manageable and easier to do. And if you keep with the habit, the payoff can be significant, and you might be surprised just how big that balance could end up becoming over the long haul.

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Investing in an S&P 500 index is a good and safe option

The world's most astute investors often advise people to invest in index funds that track the S&P 500. The S&P 500 is a collection of the leading stocks, and its performance usually indicates the overall health of the stock market. Tracking the index is a great way for novice investors to invest in stocks.

A popular, low-cost option for investors is the SPDR S&P 500 ETF (NYSEMKT: SPY). It has a low expense ratio of 0.095% which means that fees won't make much of a dent in your overall returns. On a $10,000 investment, you'd be incurring annual fees of around just $9.50. There aren't many things these days that cost you less than $10 per year. Over time, as your balance grows, so too will your fees; however, it's a worthwhile trade-off, as it means your portfolio is heading in the right direction.

For decades, investing in the S&P 500 has been a great move for investors, as the index has averaged an annual return of around 10%. That means that approximately every seven years, you would expect to see your investment double in value.

How much could a $50-per-week investment grow in the long run?

Let's suppose you invest $50 per week into the SPDR ETF. And you keep that habit up for years. Assuming you achieve an annual return of 10%, here's what your balance might look like in the future.

Table and calculations by author.

Time is the biggest factor, as the more years you have left to invest, the greater your gains will be in the long run. The key takeaway from this is that there's a significant incentive to start as early as possible, because once the balance reaches six figures, the dollar amount of those gains becomes much more substantial.

Investing early and often can be a safe way to grow your portfolio

Making modest investments into the stock market of $50 per week can be more manageable and practical than trying to save thousands of dollars first. Routinely investing in an S&P 500 index fund, such as SPY, can effectively put your investing strategy on autopilot, eliminating the need to worry about individual stocks.

As long as you have faith in the economy's long-term growth, putting money into an S&P 500 index fund is one of the safest ways you can invest for the long haul. Simply getting into the habit of investing on a regular basis can be a great decision, as it allows you to significantly build up your portfolio's balance over time.

David Jagielski, CPA has no position in any of the stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. The Motley Fool has a disclosure policy.