29 C.F.R. § 4041A.42
Method of distribution.
CFR 2016 annual edition (revised as of 2016-07-01) · current text
The plan sponsor shall distribute plan assets by purchasing from an insurer contracts to provide all benefits required by § 4041A.43 to be provided in annuity form and by paying in a lump sum (or other alternative elected by the participant) all other benefits.