member firm

n.
A securities firm with officers or partners who are members of an organized exchange.

A broker-dealer in which at least one of the principal officers is a member of either the NYSE, another major stock exchange, a self-regulatory organization or a clearing house corporation.

Also referred to as "clearing member".

Investopedia Says:
One seat (membership) on the NYSE usually costs more than $1 million!

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Brokerage firm that has at least one membership on a major stock exchange, even though, by exchange rules, the membership is in the name of an employee and not of the firm itself. Such a firm enjoys the rights and privileges of membership, such as voting on exchange policy, together with the obligations of membership, such as the commitment to settle disputes with customers through exchange arbitration procedures.

A securities brokerage firm organized as a partnership and having at least one general partner who is a member of the New York Stock Exchange. See member corporation.