Broadly speaking (i.e. not to get into asset class/composition specifics), lot to be said for using a core or more of balanced and/or tactically managed funds. Like potato chips, one might not be enough except for smallest plans, and even then...Alternatively a traditional 60:40 portfolio provides generally the same structure but with more control of underlying holdings. Maybe further overweight equities if employees can take in-service withdrawals beginning at or around normal retirement age. Maybe underweight equities somewhat if average age is particularly high.