多只证券股盘中调整，证券ETF（159841）跌逾1%，机构：行业PB估值仍在历史底部区域

Group 1 - The core viewpoint of the articles highlights the ongoing low-level fluctuations in the securities sector, with significant declines in major stocks and the performance of the largest securities ETF in the Shenzhen market [1] - The securities ETF (159841) closely tracks the CSI All Share Securities Company Index, which focuses on large-cap securities leaders in the A-share market, including both traditional and fintech leaders [1] - Six securities firms have implemented share buybacks this year, totaling over 1.2 billion, indicating a trend of companies actively optimizing their capital structure [1] Group 2 - Regulatory policies are guiding securities firms towards capital-intensive development while encouraging mergers and acquisitions to strengthen their positions, suggesting an acceleration in the supply-side structural reform process within the industry [2] - The current price-to-book (PB) valuation of the securities industry remains at historical low levels, indicating potential investment opportunities [2]