WASHINGTON — The average 401(k) balance has gone from $67,760 at the end of 1999 to $121,202 at the end of 2006, according to a new study from the Employee Benefit Research Institute and the Investment Company Institute.

The study found that most 401(k) assets are in stock. The popularity of life-cycle funds, which shift investments to “less risky” assets as people approach retirement, continues to rise, especially among new or recent hires, according to the data. The study also found that in 2006, 18% of 401(k) participants eligible for loans had taken one against their accounts. Most loans tended to be small, amounting, on average, to 12% of the remaining account balance.

Meanwhile, the share of 401(k) accounts invested in company stock continues to shrink, the data showed. The share of 401(k) participants' investments held in their employer's stock dropped 2 percentage points to 11% in 2006, continuing a steady decline that began in 1999.

The EBRI/ICI tracked participants in 401(k) plans from 1999 to 2006 each of whom held an account at the same employer during that time period. In total, the project's database contains a snapshot of account information at year-end 2006 for 20 million 401(k) plan participants.