BEIJING -Stocks on Shanghai and Shenzhen bourses saw their key indices down at the end of July compared with the end of June, according to the People’s Bank of China, the country’s central bank. At the end of July, the Shanghai Stock Exchange Composite Index closed at 3,253.2, down 145.4 points, or 4.3 percent, month on month. The Shenzhen Stock Exchange Component Index closed at 12,266.9 points at the end of last month, down 629.3 points, or 4.9 percent from the end of June. In July, the daily average turnover was 418.82 billion yuan on the Shanghai bourse, down 16.6 percent month on month, and 588.13b yuan on the Shenzhen bourse, down 2.4 percent month on month.