Asset management giant BlackRock has rolled out a set of mutual funds for 401(k) plans that involve index, rather than actively managed, investments, including index versions of its LifePath target-date retirement funds. The move points to the growing interest among retirement plan sponsors in using passively managed investments, which are usually less expensive than actively managed funds.

BlackRock now offers 16 index mutual funds for 401(k) plans, including LifePath funds dated from 2020 to 2055, a bond fund that tracks Barclay's U.S. aggregate index and funds tracking different stock indexes, such as the S&P 500, the Russell 2000 and the MSCI EAFE.

Chip Castille, managing director and head of BlackRock's U.S. and Canada defined-contribution group, says the index mutual funds are aimed at small to midsize businesses and the financial advisers who work with such companies. A large chunk of the $342 billion in defined-contribution plan assets that BlackRock manages are in index investments, but those are mostly in collective trusts, which tend to be used by bigger companies.