The chief of KB Financial Group Co., South Korea's No. 3 banking group, may be punished for a recent massive data theft at its credit card unit depending on the results of an ongoing probe, the country's financial regulator said Tuesday. Last month, the Financial Services Commission (FSC) revealed that some 20 million clients' personal data had been leaked from three credit card firms -- KB Kookmin, NH Nonghyup and Lotte -- as well as Kookmin Bank, which shared customer data with its affiliated card firm.