A Bank may act, and make reasonable charges for doing so, as trustee of any trust affecting the business of any member or any institution or group applying for membership, if:

(a) Such trust is created or arises for the benefit of the institution or its depositors, investors, or borrowers, or for the promotion of sound and economical home financing; and

(b) In the case of applicants, the Bank ceases to act as trustee if the application is withdrawn or rejected.