1) Brokerage in a stock exchange 2) Part of an exchange 3) Wall Street company 
Used for listed equity securities. Brokerage firm that has at least one membership on a major stock exchange even though, by exchange rules, the membership in the name of an employee and not of the firm itself.
A trading firm of the London Stock exchange which may deal in shares on behalf of its clients or on behalf of the firm itself.
An investment firm which is a member of the Exchange and which may deal in securities on the Exchange's market on behalf of its clients, or on behalf of the firm itself.
Used for listed equity securities. Brokerage firm that has at least one membership on a major stock
A trading firm of the LSE which may deal in shares on behalf of its clients or on behalf of the firm itself.
A trading firm on the London Stock Exchange which may act as an agency broker on behalf of clients or a principal. 
A trading firm of brokers or market makers which is a member of the London Stock Exchange. Member... <a target=_blank href='http://www.finance-glossary.com/terms/member-firm.htm?id=938&ginPtrCode=00000&PopupMode=false' title='Read full definition of member firm'>more</a>