Despite the current market slump, now is a smart time to strengthen your investment portfolio. Stock prices are down significantly over the past year, providing the perfect opportunity to load up on quality investments at a steep discount.

While the right investments for you will depend on your risk tolerance and overall investing preferences, there are three unstoppable exchange-traded funds (ETFs) you may want to stock up on in 2023.

1. SPDR S&P 500 ETF Trust

The SPDR S&P 500 ETF Trust (SPY -1.40%) is the first ETF introduced in the U.S., and it was launched in 1993. That longevity gives it an advantage over some other ETFs, because it has a long track record of earning positive average returns.

S&P 500 ETFs, in general, can be a smart investment during times of market turbulence. While they will likely take a hit in the near term if the market as a whole dips, it's extremely likely they'll recover. If you're concerned about the impact of volatility, an S&P 500 can be a safer bet.

Despite their relative safety, though, it's also possible to make a lot of money with an S&P 500 ETF. Since its inception, the SPDR S&P 500 ETF Trust has earned an average rate of return of close to 10% per year.

If you were to invest, say, $200 per month while earning a 10% average annual return, you'd accumulate close to $400,000 after 30 years.

2. Schwab Large-Cap Growth ETF

The Schwab Large-Cap Growth ETF (SCHG -2.64%) was established in 2009, and it contains 246 stocks. Around half of the fund is made up of tech stocks, but it also includes stocks from other industries, such as consumer discretionary and healthcare.

Growth ETFs are generally higher risk than broad-market funds like an S&P 500 ETF, but they can also earn much higher returns. They're designed to beat the market, meaning you're more likely to see above-average earnings with this type of ETF.

For example, since its inception in 2009, the Schwab Large-Cap Growth ETF has earned an average return of nearly 14% per year. If you were to invest $200 per month while earning a 14% average annual return, you'd have more than $850,000 after 30 years.

Keep in mind that growth ETFs do tend to experience more short-term volatility than other funds, and there are no guarantees that you'll see this type of growth over decades. But if you're willing to take the risk, the potential rewards could be lucrative.

3. Vanguard Dividend Appreciation ETF

Dividend ETFs are a little different from other funds in that they actually pay you to own them. Some companies pay a portion of their profits back to shareholders each quarter or year, which is called a dividend.

The Vanguard Dividend Appreciation ETF (VIG -0.16%) aims to track the S&P US Dividend Growers Index, which includes stocks that have increased their dividend payments for at least 10 consecutive years.

While its returns are slightly lower than the other funds on this list (earning an average return of around 9% per year since its inception in 2006), the dividend payments can help you build a source of passive income. By investing consistently, you could potentially generate a passive income stream worth hundreds of dollars per month or more.

One interesting fact about this ETF, too, is that it doesn't include stocks with the highest dividend yields. On the surface, that may seem like a negative. But it could actually lead to more growth over time, because a stock with an already high dividend yield may be unsustainable.

With this ETF, it's more likely you'll see consistent dividend increases in the future. That, in turn, could help increase your passive income payments over the long run.

As we head into the new year, now is the time to start thinking about adding new investments to your portfolio. While your investments will depend on your personal preferences and risk tolerance, these three ETFs could be smart buys in 2023.