Attorney General Tom Miller on Thursday announced agreements with online retail brokers E-Trade and TradeKing as part of a three-state investigation into potential violations of antitrust law in the retail securities brokerage industry. The investigation focused on possibly collusive conduct by several retail securities brokers and firms that assist the brokers in executing their orders on an exchange, which may have hindered competition in the retail securities brokerage industry, Miller said in a release. The two brokers agreed to create and implement an antitrust compliance policy and training program for their respective employees.  E-Trade and TradeKing also agreed to pay $200,000 to Iowa and its partner states, Connecticut and Missouri, to reimburse the states for their costs of the investigation.