With more Americans job hopping in the wake of the Great Resignation, the risk of “forgetting” a 401(k) plan with a previous employer has jumped, recent studies show.

As of 2023, there were 29.2 million left-behind 401(k) accounts holding roughly $1.65 trillion in assets, up 20% from two years earlier, according to the latest data by Capitalize, a fintech firm.

Nearly half of employees leave money in their old plans during work transitions, according to a 2024 report from Vanguard.

However, that can come at a cost.

Average 401(k) balances drop 3% amid market swings