1. A computer-based method for identifying a situation representing risk to a brokerage or its investors, comprising: receiving, at a computer system, representative of: a plurality of transactions relating to securities trading, and a plurality of entities involved in securities trading, wherein the plurality of transactions and the plurality of entities are not predetermined to be related; identifying, by the computer system, a behavior of interest comprising one or more sequence detection requirements that is indicative of a risk to a brokerage or its investors by identifying rapid switching of a first mutual fund or a second mutual fund, wherein one or more of the plurality of transactions is a solicited transaction involving one or more customers of a securities brokerage and one or more securities representatives; determining, by the computer system, whether one or more groups of the transactions and entities collectively satisfy at least one of the one or more of the sequence detection requirements; and in response to one or more groups of the transactions and entities collectively satisfying at least one of the one or more sequence detection requirements, generating, by the computer system, an alert informing a user of the one or more groups of the transactions and entities.