The alleged insider trading scandal at EADS continues to haunt the company, its directors and core shareholders. On Wednesday, Lagardère, the French industrial shareholder of the Franco-German aerospace group, revealed it had received what it called a threatening letter from lawyers working for Crédit Mutuel.

Back in 2006, the mutual bank was one of the French institutions that bought convertible bonds issued by Lagardère to cut its stake in EADS from 15 per cent to 7.5 per cent. Soon after Lagardère issued the bonds convertible into EADS shares, the aerospace group’s value started tumbling on the back of surprise profit warnings over delays and technical problems at its Airbus civil aircraft affiliate. The EADS stake being sold was worth more than €2bn ($3.1bn).