Last year was a pretty good year if you were among the tens of millions of employees who put their savings to work in a 401(k) plan.

Sure, strong returns on the S&P 500 helped. It rose nearly 25% for the year. Same goes for the Nasdaq, which was up about 32%. And bonds made small gains — the S&P Aggregrate Bond Index, for instance, increased by roughly 2.25%.

But you deserve some credit, too.

Based on the latest data from Fidelity and Vanguard, in 2024 many employees increased their savings rates, participants stayed diversified, and the vast majority didn’t tap their accounts for a loan or hardship withdrawal.

Also helpful: Many benefited from 401(k) plans that are now better designed to encourage sustained savings and diversified investing.

What 401(k) participants accumulated

Fidelity reported that as of the end of the fourth quarter in 2024, the average 401(k) balance had risen by 11% for the year to $131,700. That’s based on its database of more than 24.5 million accounts.

Vanguard, using its database of 5 million accounts, reported that the average balance was $148,153, up about 10% from the year prior.

Averages, of course, don’t shed light on groups who have built up the largest 401(k) balances, relatively speaking, and those who haven’t (yet).

For instance, Fidelity found that by the end of last year, the number of 401(k) accounts with balances of at least $1 million had risen 27% to 537,000, up from 422,000 at the end of 2023.

Which participants had such high balances? More than half (57%) were Gen Xers, 41% were Baby Boomers and 2% were Millennials, according to Fidelity. But, overall, the so-called “millionaire” accounts only represent 2.2% of accounts tracked by Fidelity.

A far larger share of participants — roughly 50% — had balances that fell below the median line. At Fidelity, the median balance at the end of 2024 was $30,700, up 13% from the end of 2023. At Vanguard it was $38,176, up 8%.

Beyond market returns: Time and consistency are essential

Given the willful chaos and uncertainty being generated by the Trump administration, there is no telling what the markets and the US economy will do in the foreseeable future.

However it goes, you will remain in control of key variables: How much you save, how consistently you save and how you invest the money.

For most people who don’t land jobs with seriously fat paychecks, the secret sauce to building financial security for yourself is saving consistently in every year of your career and investing that money in a diversified portfolio that lets you benefit from gains during bull markets while protecting you from the worst declines in bear markets.

The average savings rate last year was 14.1%, up slightly from a year ago, Fidelity found. That represents the combination of employee contributions (9.4%) plus employer matches (4.7%). Fidelity found that close to 40% of retirement savers increased their contribution rate in 2024. Vanguard found that 45% did so, either on their own or because their plan was set up to automatically increase deferral rates annually.

Time spent saving is also key to building up a healthy balance. Among Fidelity’s million-dollar-plus accounts the average person had been saving for 26 years. And for Gen Xers — the next group of workers to retire — those who had been saving for at least 15 years had an average balance of $589,400.

As for allocation and diversification, Vanguard found that two-thirds of participants (67%) in its database had professionally managed allocations — meaning they invested in a target-date fund, a traditional balance fund or a managed account. That fact, Vanguard said, has “dramatically improved” participants’ age-appropriate equity exposure.

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