Average 401(k) account balance by age group

According to Fidelity, the average 401(k) balance rose 12% in 2012 to $77,300. Based on 20,500 record-kept plans and 12 million participants, those age 55 and older had an average account balance of $143,300 as of Dec. 31. The average balance for Generation Y (those born between 1978 and 1991) was $15,400.