ORANGE COUNTY

Riverboat Casino: Irvine-based Excalibur Holding Corp. said Thursday that it has signed a letter of intent for a joint venture with Bally Manufacturing Corp. The project involves leasing property in Tunicia, Miss., purchasing a riverboat and converting it into 25,000- to 30,000-square-foot dockside casino. Bally would be the controlling partner in the Tunica casino, which could open by the end of this year. Excalibur, the Irvine-based holding company for a thoroughbred racetrack complex in West Virginia, agreed separately to purchase Regal Casinos Inc.’s interest in the Tunicia venture. Excalibur Holding Corp. is not connected to the Excalibur hotel and casino in Las Vegas. In Thursday’s trading on the NASDAQ market, Excalibur’s stock closed at $11.88 a share, down 87.5 cents.