Here's a simple truth about getting rich for retirement, courtesy of a bunch of new 401(k) millionaires: most of them didn't beat the market. They just owned it.

Think about that for a second. The secret sauce isn't some brilliant, high-frequency trading algorithm or a hot tip on the next big thing. It's the financial equivalent of showing up to work every day and putting money in a box that owns a little bit of everything. New data from Fidelity Investments, cited by Yahoo! Finance, shows this approach is working spectacularly well for more people than ever. The number of 401(k) millionaires—people with over a million bucks saved in their employer plan—rose to a record 665,000 by the end of 2025. The average account balance jumped 11% to $146,100. And this happened in a year that, let's remember, had its fair share of market wobbles.

Why? Well, the markets were very kind in 2025. The S&P 500 was up almost 17%, the Nasdaq Composite rallied more than 20%, and the Russell 2000 gained about 13%. That's a great tailwind. But for the long-term savers who actually became millionaires, the key wasn't just the market's generosity. It was their own discipline. According to the latest Fidelity data, workers are saving at an average rate of 14.2% of their pay when you include employer contributions. Even more impressive, nearly 40% of employees actually increased their savings rate this year. So it's a two-part story: the market went up, and people kept shoveling money into it.

So, Where Do ETFs Come In?

Now, most 401(k) plans themselves are built on mutual funds or target-date funds, not exchange-traded funds (ETFs). But the philosophy behind a successful 401(k)—broad, low-cost market exposure—is exactly what ETFs are built for. For investors building retirement portfolios in other accounts, like IRAs or regular brokerage accounts, ETFs offer a nearly identical path.

Low-cost index ETFs let you track the same market benchmarks that are doing the heavy lifting in those million-dollar 401(k)s. Want the kind of broad U.S. stock exposure that forms the core of most retirement plans? You might look at something like the Vanguard Total Stock Market ETF (VTI) or the SPDR S&P 500 ETF Trust (SPY). They're simple, they're cheap, and they own the market so you don't have to try to outsmart it.

And let's not forget the other half of the equation: bonds. As someone gets closer to retirement, dialing back risk with some fixed income is standard practice. Bond ETFs, like the iShares Core U.S. Aggregate Bond ETF (AGG), are a popular tool for this, adding stability to a portfolio when stock markets get choppy. This balanced approach is the norm. Fidelity's data shows that fewer than 7% of retirement savers have a portfolio of 100% stocks. Everyone else has mixed in some bonds, because the goal isn't just growth—it's reliable growth you can retire on.

The Real Magic: Consistency

Let's circle back to that savings rate. An average of 14.2% (with the employer match) is no small thing. And the fact that 40% of people managed to save more this year is a powerful behavioral signal. This discipline, paired with that long-term, buy-the-whole-market exposure, is the engine that creates retirement wealth over decades.

For an investor outside of a company 401(k) plan who wants to copy this playbook, the blueprint is straightforward. Use diversified ETFs that track major stock and bond indexes. They offer a simple, low-cost way to stay invested through the ups and downs and simply collect your share of the market's long-term growth. The story of the 401(k) millionaire isn't a story of luck or genius. It's a story of consistency and owning the haystack instead of searching for the needle.