Jean-Marie Messier, the former head of Vivendi Universal, was placed under formal investigation for alleged stock market rigging by the French media and entertainment group. Messier, 47, who had been in police custody since Monday, was freed on bail after the move by French investigating magistrates, which is just one step shy of formal charges. French investigators are probing events during Messier's tumultuous term, which took Vivendi from a simple utilities company to a vast international media empire which is now flirting with bankruptcy.