For many years there were rather "high walls" that kept different types of products and services completely separate – a bank did banking, a broker sold only securities, and insurers limited themselves to insurance.
In recent years many of the walls separating these different financial services have been lowered. For example, you can buy securities and insurance at many bank offices, insurance companies pay claims by issuing a "checkbook instead of a check" to beneficiaries, and securities brokers provide access to insurance, mortgages, CDs and banking-like services.
Most of these developments have been the result of innovative relationships that financial services have structured among themselves, in terms of service agreements and joint ventures. Others have been the result of legal and regulatory changes that have allowed cross-ownership and permitted previously impermissible acquisitions.