Institutional Account is an account in the name of an institution, operated for the benefit of others, i.e. banks and mutual funds. There is no minimum size for an institutional account.
Applying "Institutional Account" to Securities Exams:
Institutions are often exempt from many securities laws, as these laws were designed to protect the individual. Although there is no minimum account value to be labeled institutional, institutions are expected to be more savvy than individuals; and more able to ascertain and bear risk. Other examples of institutions are Insurance Companies and Broker Dealers.