How do I investigate 401(k) investment choices?

My 401(k) is dropping a mutual fund in which I invested. The plan administrator has given me the option of a growth and income fund that is “managed exclusively for the fund.” There’s no ticker symbol. How can I vet the fund with an independent rating site? And are those funds common in 401(k)s? —D.S., address not disclosed

Almost half of the assets in 401(k) plans aren’t invested in mutual funds, according to the Investment Company Institute, a mutual-fund industry trade group. Increasingly, assets are invested in products that aren’t always as transparent as mutual funds. Your plan may have chosen to replace your fund with what’s known as a collective investment, which is managed by a trust or a bank, perhaps to reduce overall costs. Although you might not have access to the day-to-day performance of those replacements, the Department of Labor still requires 401(k) providers to furnish participants with certain performance data and costs. You should ask your employer for those details. —Consumer Reports