No association shall invest in any security under this chapter, other than in liquid assets, or in any loan at any time if the association fails to meet the minimum liquidity requirements prescribed by Section 566.2 of Title 12 of the Code of Federal Regulations, unless the commissioner has issued prior written approval. “Liquid assets,” as used in this section, has the same meaning as defined by the regulations codified in Section 566.1 of Title 12 of the Code of Federal Regulations.