From this survey, it must not be concluded that the banking structure of the United States is composed of a number of groups of specialized institutions, for there has been comparatively little tendency toward specialization in the field of banking proper. A large commercial bank has frequently absorbed a trust company, or, on the contrary, a progressive trust company, desirous of entering into commercial banking, has at times taken over a long-established national bank. These mergers have resulted in powerful banking institutions which have further extended their activities to include other fields of finance, by opening departments for receiving time deposits and also by operating securities departments for handling investments. A large modern bank is therefore able to offer its customers practically every possible financial service in much the same manner that a department store places on sale goods of every description.