The average 401(k) balance in workplace retirement plans for which Fidelity is the recordkeeper hit an all-time high in the last quarter of 2019, at $112,300.
That marked a 7% increase from the third quarter of last year, and a 17% increase from the end of 2018.
And it's nearly double the average balance of $62,600 at the end of 2009, when retirement savers were still reeling from the retirement crisis and beginning to recover from 2008's pillage.
Strong equity markets are behind record-breaking averages. Last year alone, the S&P 500 returned 28.9%, just shy of 2013's 29.6%.
The index has only had two losing years since the financial crisis, in 2015 and 2018.
But Fidelity's data shows that improved plan design and better savings habits have also influenced higher accounts.
The average individual savings rate was 8.9% in the fourth quarter of 2019, also a record high. When accounting for employer matches, the average savings rate was 13.5%.
Last year, one-third of employees increased their savings rate by an average of 3%. Four in 10 did so on their own; six in 10 were increased via auto-escalation features.