A Scottrade customer is suing the St. Louis discount brokerage over a breach of its system that impacts 4.6 million customers. Andrew Duqum, of St. Louis County, on Wednesday filed the lawsuit in U.S. District Court for the Eastern District of Missouri. It seeks class-action status. Duqum opened an account with Scottrade in late 2013, and his personal information was exposed because of the breach, according to the lawsuit.