Last year's stock-market surge boosted 401(k) accounts, but millions of Americans are still likely to run short of money in retirement, according to a pair of studies released Thursday.
The average 401(k) balance reached a new record of $89,300 in the fourth quarter, up 15.5% from a year earlier, according to mutual-fund giant Fidelity Investments. More than three-quarters of the gain came from rising stock prices.