Who is a broker-dealer?

http://www.infopediaonline.com/home/financial-terms--definitions/broker-dealer

A broker-dealer is a firm who purchases and sells stocks/securities on behalf of its client/customer. In such cases they act as brokers.

They also purchase stocks/shares in their own account. In this scenario they act as dealer.

They are sometimes referred to as Registered Representative (RR).

http://www.infopediaonline.com/home/financial-terms--definitions/broker-dealer