Banks and closely related institutions, such as currency exchanges, clearing house associations, corporations for banking abroad and agencies of foreign banks; credit agencies other than banks such as rediscount and financing institutions, mortgage companies, industrial loan institutions, agricultural credit agencies, sales finance and industrial credit companies and personal credit companies; co-operative credit societies; investment companies; holding companies; security brokers and dealers; underwriters of financial security issues; security exchanges and exchange clearing houses; bullion exchanges and other financial institutions such as those engaged in patent buying and licensing and those organized for the protection of security holders.