The practice in which a
broker conducts a
transaction on his/her own account after filling a similar
order on behalf of a client. For example, if a client
sells 10,000
shares and the broker owns some shares in the same company, he may piggyback by selling his own shares. A broker piggybacks when he/she believes that the client has
insider information, or at least a better understanding than the broker on the
market's future movements. Piggybacking should not be confused with
piggy back registration, which is a different concept altogether.