29 CFR §2550.407a-1

1. (a)In general. Section 407(a)(1) of the Employee Retirement Income Security Act of 1974 (the Act) states that except as otherwise provided in section 407 and section 414 of the Act, a plan may not acquire or hold any employer security which is not a qualifying employer security or any employer real property which is not qualifying employer real property. Section 406(a)(1)(E) prohibits a fiduciary from knowingly causing a plan to engage in a transaction which constitutes a direct or indirect acquisition, on behalf of a plan, of any employer security or employer real property in violation of section 407(a), and section 406(a)(2) prohibits a fiduciary who has authority or discretion to control or manage assets of a plan to permit the plan to hold any employer security or employer real property if he knows or should know that holding such security or real property violates section 407(a).
2. (b)Requirements applicable to all plans. A plan may hold or acquire only employer securities which are qualifying employer securities and employer real property which is qualifying employer real property. A plan may not hold employer securities and employer real property which are not qualifying employer securities and qualifying employer real property, except to the extent that:
   1. (1)The employer security is held by a plan which has made an election under section 407(c)(3) of the Act; or
   2. (2)The employer security is a loan or other extension of credit which satisfies the requirements of section 414(c)(1) of the Act or the employer real property is leased to the employer pursuant to a lease which satisfies the requirements of section 414(c)(2) of the Act.