BT Group Plc directors and their relatives bought more than $700,000 of its stock Monday and Tuesday, providing a vote of confidence in the former British telecommunications monopoly one week after it suffered a 21 percent drop. The purchases, totaling more than 185,000 shares, were led by Anthony Ball, the former BSkyB chief executive officer and current BT board member, who bought 70,000 shares, and relatives of Chairman Mike Rake and audit & risk committee chairman Nick Rose, who bought 90,000 shares combined, according to a regulatory filing Tuesday.