Saving for the future isn't easy, but investing in the stock market can make your goals much more achievable. However, it's crucial to invest in the right places.

There are countless options when it comes to building wealth in the stock market, but if you're looking for a low-maintenance investment that can help you make a lot of money with little effort, an exchange-traded fund (ETF) can be a good choice.

Each ETF contains dozens or even hundreds of stocks, all bundled together into a single investment. This not only takes the guesswork out of where to invest, but also provides ample diversification -- which can limit your risk.

While everyone's investing preferences will be different, there's one ETF that could help you turn $100,000 into $1 million or more with next to no effort on your part: the Invesco QQQ Trust (QQQ 1.54%).

Building long-term wealth in the stock market

Invesco QQQ is a tech-focused ETF that tracks the Nasdaq 100 index, which contains the 100 largest nonfinancial stocks within the Nasdaq. This includes stocks from the "Magnificent Seven," or Apple, Microsoft, Alphabet, Amazon, Nvidia, Meta Platforms, and Tesla.

As a growth ETF, Invesco QQQ is designed to beat the market -- something it's successfully done in the past. Over the past five years alone, QQQ has earned total returns of more than 132%, compared to the S&P 500's roughly 69% returns in that time.

The fund's 10-year performance is even more promising, earning returns of more than 350%, while the S&P 500 saw returns of just 155%. While past performance doesn't predict future returns, this ETF has a long track record of outperforming the market.

Its average return over the past 10 years is around 17% per year, meaning all the highs and lows have averaged out to around 17% annually over the last decade. To play it safe, though, let's assume this fund only earns a 12% average annual return going forward -- which is only slightly higher than the market's historic average of around 10% per year.

If you already have $100,000 in savings and are earning a 12% average annual return, you'd reach roughly $1 million in savings after about 21 years -- even if you don't make any additional contributions. If you can invest a little each month, you could potentially reach your goal even faster.

Risks to consider before you buy

Invesco QQQ could be a smart investment for those looking to supercharge their savings, but growth ETFs are often riskier than broad-market funds like S&P 500 ETFs.

Because this fund is focused primarily on tech stocks, it offers less diversification than an ETF that includes stocks from many different industries. Also, because the tech sector is generally more volatile, you can expect to see more severe ups and downs when the market is turbulent.

If you're willing to take on those risks for the chance to earn higher-than-average returns, this ETF could be a good fit. Just be sure the rest of your portfolio is well diversified, and do your best to keep a long-term outlook.

There are plenty of great investments out there that can help you build long-term wealth, and not all of them will be the right fit for all investors. Invesco QQQ has a history of beating the market, but it does come with higher risk than some other ETFs. If that's a worthwhile trade-off for you, it could be a good addition to your portfolio.