化学制药板块9月18日涨0.47%，迈威生物领涨，主力资金净流入2.43亿元

Group 1 - The chemical pharmaceutical sector increased by 0.47% on September 18, with Maiwei Biotech leading the gains [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] - Notable performers in the chemical pharmaceutical sector included Maiwei Biotech, which rose by 13.21% to a closing price of 54.75, and Xinnoway, which increased by 7.07% to 51.80 [1] Group 2 - The net inflow of main funds in the chemical pharmaceutical sector was 243 million yuan, while retail funds experienced a net outflow of 18.46 million yuan [2] - The top stocks by main fund inflow included Maiwei Biotech with 319 million yuan and Borui Pharmaceutical with 214 million yuan [3] - Retail investors showed significant outflows in several stocks, including Maiwei Biotech and Borui Pharmaceutical, indicating a shift in investor sentiment [3]