Alliant Techsystems Inc. is merging its aerospace and defense groups with Orbital Sciences Corp. into a new company named Orbital ATK Inc., it was announced Tuesday. Alliant, in Arlington, Va., maintains its defense electronics system division in Northridge. That division performs research and development and manufacturing of weapon systems for the Pentagon. The division has about 250 employees and also has facilities in Texas and Florida. The combination of the ATK aerospace and defense groups with Orbital Sciences, in Vienna, Va., which builds rockets to launch satellites and missiles, results in a company with revenue of more than $4 billion. The merger is expected to close by the end of the year. Management at security software developer XYPRO Technology Corp. in Simi Valley completed on Tuesday their buyout of the company from its founders and previous owners. The buyout positions the company to grow with the industry and its customers, said Lisa Partridge, XYPRO chief executive. Changes at the company include naming Andrew Price to vice president of technology, promoting Richard Nissenbaum from controller to chief financial officer and moving Ellen Gershev from quality assurance manager to director of engineering. XYPRO founders Dale Blommendahl and Sheila Johnson will remain on the company’s board of directors. Wellpoint Inc., the parent company of Anthem Blue Cross in Thousand Oaks, reported financials Wednesday that beat analyst expectations for net income but missed on revenue. The Indianapolis insurer reported net income of $701 million ($2.40 a share) in the first quarter ended March 31, compared to $885 million ($2.89 a share) for the same quarter a year ago. Operating revenue grew incrementally to $17.6 billion. Analysts expected earnings of $2.10 a share on revenue of $18 billion, according to FactSet. Shares closed up$5.29 or 5.3 percent to $100.68 in trading on the New York Stock Exchange.