Apple shares fell for the second day in a row, after reports that Chinese government employees were banned from using iPhones. The company’s stock market value has fallen by more than 6 percent, or nearly $200 billion, in just the past two days. China is the third largest market for the American technology giant, representing 18 percent of Apple’s total revenues last year. The company also manufactures most of its products through its largest supplier, Fox Conn, of China.