Choosing the right investments is key to generating wealth in the stock market, but with so many options to choose from, it can be overwhelming at times to build a robust portfolio. The key to choosing solid investments is to focus on the long term. Although long-term investments may experience volatility over weeks or months, over several years, they're more likely to see consistent growth.

Regardless of where you invest, it's unrealistic to expect to make a substantial amount of money overnight. However, it's possible to build wealth over time, and by investing consistently, you may even become a millionaire. And there's one ETF, in particular, that can help you get there.

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Choosing the right ETF

ETFs can be a smart investment for many people because they require less research and make it easier to build a diversified portfolio. Each ETF may contain hundreds or even thousands of stocks, which limits your risk. One ETF that could be a smart addition to your portfolio is the Schwab U.S. Large-Cap Growth ETF (SCHG -2.22%).

This fund includes nearly 230 stocks from some of the largest and strongest companies in the U.S., such as Amazon, Microsoft, and Apple. All of the stocks within this ETF also have the potential for rapid growth, so there's a better chance this fund could earn above-average returns over time.

One thing to keep in mind before investing in this fund is that growth ETFs can pose more risk than other broad-market ETFs. Growth stocks often experience higher returns than their more established counterparts, but they can also be more volatile.

For that reason, it's wise to make sure that this isn't the only investment in your portfolio. This ETF can be a smart investment, but by investing in other stocks or indexes, as well, you can better diversify your portfolio and limit your risk.

How much can you earn with this ETF?

First, it's important to note that past performance doesn't always equate to future returns. In other words, simply because an investment has earned certain returns in the past doesn't necessarily mean it will continue earning those returns over the long term.

That said, an investment's historic returns can help you gauge approximately how much your savings could grow over time. Since the Schwab U.S. Large-Cap Growth ETF was launched in 2009, it has earned an average rate of return of around 17% per year.

Again, this doesn't necessarily mean you'll earn 17% returns each and every year with this ETF. This fund, in particular, has earned higher-than-average returns because it was created at the tail end of the Great Recession, and since then it has experienced one of the greatest bull markets in history. For that reason, it's highly unlikely you'll earn 17% average returns over the long run.

However, that doesn't necessarily mean this ETF isn't a good investment or that you can't make a lot of money. Say that instead of earning 17% average annual returns, you earn a 13% average annual return. If you were investing $100 per month, here's approximately how much you could potentially earn over time:

Number of Years Total Savings
20 $97,000
25 $187,000
30 $352,000
35 $656,000
40 $1,216,000

Source: Author's calculations via Investor.gov.

Keep in mind that there are never any guarantees when it comes to the stock market, and even 13% average annual returns may be difficult to achieve. But it's still possible to reach millionaire status, even if you're only earning average returns.

Say, for example, your investments only earn a 10% average annual return over the long run, which is in line with the S&P 500's historic average. In this case, you could reach $1 million in savings by investing around $200 per month for 40 years.

Investing in the stock market is one of the most effective ways to build long-term wealth, but choosing the right investments is critical. By investing a little each month and keeping your money invested for as long as possible, you can earn more than you might think.