The stock market's hot streak has had a clear effect on voluntary retirement savings plans in the United States, known as 401(k)s and IRAs. The number of contributors with a balance of $1 million or more in their accounts at Fidelity Investment-the largest administrator of these accounts in the country-stood at 485,000 in the first quarter, up 43% from March 2023. Average account balances also jumped, standing at $125,900 for 401(8k) accounts and $127,745 for IRAs, the highest level since late 2021.

But despite the sharp increase in million-dollar balances, they still represent an absolute minority: about 2% of the system's 24 million accounts. still represent an absolute minority: about 2% of the 24 million accounts in the system. The median balance for 401(k) accounts is $28,900 and for IRAs is $15,000, according to Bloomberg.

Not surprisingly, the profile of those with balances of US$1 million or more corresponds to people with seniority in the system: on average they have been contributing for 26 years, with an average contribution of 17% of their income.

401(k) and IRA accounts are tax-advantaged savings plans designed for retirement savings and in many cases receive contributions from both employees and their employers. Inflation in recent years, however, has made it more difficult for average U.S. workers to participate in these voluntary savings plans. Nearly 40% do not have access to them and a similar percentage of retirees rely exclusively on Social Security income.