(a) For the purposes of this subchapter, a pension trust is an express trust:
(1) containing or relating to property;
(2) created by an employer as part of a stock-bonus plan, pension plan, disability or death benefit plan, or profit-sharing plan for the benefit of some or all of the employer's employees;
(3) to which contributions are made by the employer, by some or all of the employees, or by both; and
(4) created for the principal purpose of distributing to the employees, or the successor to their beneficial interest in the trust, the principal or income, or both, of the property held in trust.
(b) This subchapter applies to a pension trust regardless of when the trust was created.