工程咨询服务板块12月11日跌2.5%，矩阵股份领跌，主力资金净流出2.99亿元

Group 1 - The engineering consulting services sector experienced a decline of 2.5% compared to the previous trading day, with Matrix Co. leading the drop [1] - The Shanghai Composite Index closed at 3873.32, down 0.7%, while the Shenzhen Component Index closed at 13147.39, down 1.27% [1] - A detailed table of individual stock performance within the engineering consulting services sector is provided [1] Group 2 - The net outflow of main funds in the engineering consulting services sector was 299 million yuan, while retail funds saw a net inflow of 209 million yuan [2] - The sector also recorded a net inflow of 89.14 million yuan from speculative funds [2] - A detailed table of fund flows for individual stocks in the engineering consulting services sector is included [2]