If I remember this article correctly https://www.wsj.com/personal-finance/retirement/the-401-k-rollover-mistake-that-costs-retirement-savers-billions-c7a19dfa?r

If I remember this article correctly https://www.wsj.com/personal-finance/retirement/the-401-k-rollover-mistake-that-costs-retirement-savers-billions-c7a19dfa?reflink=desktopwebshare_permalink https://www.wsj.com/personal-finance/retirement/the-401-k-ro..., the summary is some peoples' 401k accounts are not invested in the stock market. Rather the money sits for years collecting interest, growing far less.