Security Trust Co. of Arlington, Tex., which...

Security Trust Co. of Arlington, Tex., which issued MasterCard secured credit cards throughout the United States, has been declared insolvent by state banking officials. Texas Banking Commissioner Kenneth Littlefield said in a prepared statement that Security Trust was closed Sept. 15., and warned that because of the closure, MasterCards issued to 11,000 customers are invalid. Littlefield also said no new applications or deposits for Security Trust should be sent to EquiSystems Inc. of Rancho Cordova, Calif., which formerly acted on behalf of Security. Cardholders should, however, continue to make monthly payments as they become due, Littlefield said.