Recently, when reviewing investment portfolios, I came across a pretty interesting issue. A lot of people hold S&P 500 index funds, which is indeed a solid long-term choice—but have you ever wondered whether this index has actually become a bit different now?

The S&P 500’s return over the past 20 years is close to 695%, and that number definitely looks tempting. But there’s a catch behind it—this index is increasingly dominated by tech stocks. The combined market value of Nvidia, Apple, and Microsoft exceeds 11 trillion, and their share in the Vanguard S&P 500 ETF is already more than 20%. In plain terms, it’s a small number of tech giants that are determining the ups and downs of the whole index.

This has both pros and cons. Tech stocks do make money fast—Nvidia rose by nearly 1000% over three years—but they’re also very volatile. If you invested in an S&P 500 ETF expecting stable returns, you’re now facing higher risk, especially during periods of market turbulence. Remember the bear market in 2022? Tech stocks fell the hardest, and this Vanguard ETF got hit hard as well.

So some people came up with another idea—the Invesco equal-weight S&P 500 ETF. This fund tracks the S&P 500 too, but each stock has roughly the same weight, whether you’re talking about a tech giant or a traditional company, they each take up the same proportion. The benefit of doing this is that risk is more spread out, and no single stock or any particular industry can affect the fund too much.

But there is a cost. When star stocks have the same weight as regular stocks, those super-profitable companies can’t lift the fund’s overall performance as much. Over the past 10 years, Vanguard’s S&P 500 ETF has clearly performed better—especially in the past few years amid the wild growth of tech stocks. But before 2020, the performance of the two funds was actually pretty similar.

The problem now is that if tech stocks continue to lead—especially if AI-related stocks keep running hot—this gap could keep widening. But on the flip side, if the market pulls back, the equal-weight ETF could be more resilient.

So which one you choose really depends on your own risk tolerance. If you can accept volatility and want to pursue tech-driven growth, Vanguard’s 500 ETF may be a better fit for you. But if you value stability more and want to reduce risk and volatility, Invesco’s equal-weight version may be the smarter choice. Both of these ETFs are good tools for tracking the S&P 500—the key is finding the one that suits you best.