All banks, bank and trust companies, trust companies, savings banks, private banks, building and loan associations, credit unions and saving and loan associations organized under the laws of this Commonwealth or the United States and all insurance companies, pension funds and trusts, the State Employes' Retirement Fund, the Public School Employes' Retirement Fund, and corporations and associations approved by the board of directors, may invest in loans guaranteed or made by the agency for the payment of expenses incurred or to be incurred in acquiring an education at a postsecondary institution of higher learning. Any bank, banking institution or trust company, and savings and loan association which is designated as a depository for State moneys shall be permitted to pledge notes representing State or Federally insured loans to students or parents of students as collateral for the deposit of State funds or any of its political subdivisions and the market value of such pledge of student loans shall approximate no less than 120% of the value of the funds deposited.