Istanbul, April 15 () – U.S. Securities and Exchange Commission (SEC) has charged Volkswagen and former CEO Martin Winterkorn with defrauding investors during its diesel emissions scandal. The charges come two years after Volkswagen settled with the U.S. over criminal and civil charges. The SEC said that between April 2014 and May 2015, Volkswagen issued more than 13 billion dollars in bonds and asset-backed securities in U.S. markets when senior executives knew that more than 500 thousand vehicles in the country grossly exceeded legal vehicle emissions limits. Winterkorn made false and misleading statements to investors and underwriters about vehicle quality, environmental compliance, and the company's financial standing, which gave Volkswagen a financial benefit when it issued securities at more attractive rates for the company, according to the SEC. "Volkswagen hid its decade-long emissions scheme while it was selling billions of dollars of its bonds to investors at inflated prices," said Stephanie Avakian, co-director of the SEC's enforcement division. In September 2015 Volkswagen installed software on more than 475 thousand cars that enabled them to cheat on emissions tests, according to the Environmental Protection Agency. The software reduced nitrogen oxide emissions while the cars were placed on a test machine but allowed higher emissions and improved engine performance during driving. In 2016 the Justice Department sued Volkswagen over the emissions-cheating software and the Federal Trade Commission sued the company, stating it made false claims in commercials promoting its "Clean Diesel" vehicles as environmentally friendly.