401(k) millionaires hit a record high of 654,000 in September, up from 595,000 in June, with millennials making up the largest group. The average 401(k) balance is $144,400, and the average IRA balance is $137,902, both increasing by 5% from June.

Millennials are starting to reach the million-dollar milestone in their 401(k)s, a change from the historically Boomer and Gen X-dominated group. Fidelity reports a 3.7% increase in millennial millionaires, up from 1.8% last year, with Boomers at 36%, Gen X at 60%, and millennials at 4%.

Women’s average account balances surpassed half a million dollars for the first time, reaching $501,100, a 16.5% increase from last year. The total average 401(k) savings rate is 9.5%, with an average employer contribution rate of 4.7%, resulting in a record high combined contribution rate of 14.2%.

Despite the rise in millionaires, nearly 20% of Fidelity account participants have outstanding loans, and 2.8% took hardship withdrawals. The market can impact the number of millionaire savers, and they make up a small percentage of Fidelity’s retirement savers.

Withdrawals from 401(k) accounts are typically taxed as ordinary income, with a 10% early withdrawal penalty before age 59½, unless you meet IRS exceptions like medical expenses or first-time home purchases. Some employer plans allow non-hardship withdrawals.

Read more at Yahoo Finance: Millionaire millennials everywhere? New Fidelity survey highlights the status of retirement savers.