燃气板块9月18日跌1.58%，天壕能源领跌，主力资金净流出1.61亿元

Group 1 - The gas sector experienced a decline of 1.58% on September 18, with Tianhao Energy leading the drop [1] - The Shanghai Composite Index closed at 3831.66, down 1.15%, while the Shenzhen Component Index closed at 13075.66, down 1.06% [1] - A detailed table of individual stock performance in the gas sector is provided [1] Group 2 - The gas sector saw a net outflow of 161 million yuan from main funds, while retail investors contributed a net inflow of 85.72 million yuan [2] - The net inflow from speculative funds was 7.49 million yuan [2] - A detailed table of fund flows for individual stocks in the gas sector is included [2]