Fund of Mutual Financial Aid of the credit union can be extended by sponsorship contributions from businesses, organizations, including on a returnable basis. Like the credit cooperatives, credit unions form associations of a higher level, which are called corporate credit unions. To reduce the risk of default on loans members of the credit union shall the joint guarantee. Until the 70's there was a proliferation of the U.S. credit unions due to the increase of their number and the number of shareholders, although it must be acknowledged that there was also and a qualitative growth. Credit unions historically formed as a special form of social support, initially taken upon themselves the social mission of protecting the interests of citizens in the field of financial services. A credit union on its own initiative order is created by citizens (individuals) to solve their financial problems that they could not solve in other financial institutions.