Volkswagen AG lost almost a quarter of its market value after it admitted to cheating on U.S. air pollution tests for years, risking billions in potential fines and a backlash from consumers in the world's second-biggest car market.<br />The shares plunged as much as 23 percent to 125.40 euros in Frankfurt, extending the stock's slump for the year to 31 percent.<br />The drop wiped out about 15.4 billion euros in value.<br />Volkswagen Chief Executive Officer Martin Winterkorn said on Sunday that the company is cooperating with the probe and ordered its own external investigation into the issue.<br />The CEO said he was "deeply sorry" for breaking the public's trust and that VW would do "everything necessary in order to reverse the damage this has caused."
