In many 401(k) retirement plans, investor contributions are directed to target-date funds, unless otherwise specified, reports Karen Damato for the Wall Street Journal.

Consequently, target-date strategies attracted an estimated 36% of contributions to 401(k) plans last year, according to Cerulli Associates data.

The research firm projects that the share could steadily increase to 63% by 2018 while the share of 401(k) assets in target-date choices will expand to 35% in 2018 from an 17% in 2013.

For more information on life-cycle funds, visit our target-date ETFs category.

Max Chen contributed to this article.