The number of 401(k) and IRA millionaires also declined, according to Fidelity. Those people with $1 million or more in their 401(k) plans dropped to 133,800 at the end of the fourth quarter, while the number of people with $1 million or more in their IRAs fell to 138,800.

Despite the fact that balances fell, there were a few positive trends among savers.

First, people did not make dramatic changes to their investments, despite the market volatility, Fidelity's data shows. Just 5.6 percent of account holders made significant changes to their asset allocations in the fourth quarter.

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Second, the portion of investors who regularly contribute to their retirement savings accounts rose to more than 99 percent in the fourth quarter — the highest since the first quarter of 2011. In 2018, the average total 401(k) contribution was $6,850 and the average total IRA contribution was $4,200.

Third, the number of workers who took loans from their 401(k) plans dropped to a 10-year low. The portion of workers with outstanding loans from their 401(k) plans fell to lowest level since the second quarter of 2009, according to Fidelity.



