TOKYO: The head of the Tokyo Stock Exchange has stepped down after accepting responsibility for an unprecedented day-long shutdown of one of the world's biggest markets, the operator said Monday. A hardware glitch suspended transactions for a day on Tokyo's two leading indexes last month, as well as smaller exchanges in other parts of Japan. TSE president Koichiro Miyahara "has taken seriously his responsibility for the failure in the... trading system," the Japan Exchange Group (JPX), which operates TSE, said in a statement.