化工行业周报：维生素D3价格大涨，原油价格下跌

Investment Rating - The report maintains a "Positive" investment rating for the chemical industry [1]. Core Viewpoints - The overall market index has declined, with the Shanghai Composite Index closing at 2890.90, down 3.07% for the week, and the chemical sector specifically down 3.70% [3][8]. - Key stocks in the chemical sector showed significant fluctuations, with top gainers including Fengguo Co. (+26.98%) and Lekai Film (+13.41%), while major losers included Shuangle Co. (-17.19%) and Tongyi Co. (-15.35%) [13][15]. - The report highlights a notable increase in the prices of Vitamin D3, formic acid, and anionic surfactants, while significant declines were observed in liquid gas and isobutanol prices [18][19]. Summary by Sections Recent Market Performance - The chemical sector has experienced a decline of 3.70% this week, with the overall market indices also showing downward trends [8][9]. - The top-performing sub-sectors included textile chemical products (+0.69%) and inorganic salts (+0.05%), while coal chemical (-9.70%) and nitrogen fertilizers (-8.14%) faced the largest declines [10]. Chemical Product Price Changes - The report notes that Vitamin D3 prices increased by 18.92% to 220 CNY/kg, driven by supply tightness [18][21]. - Formic acid prices rose by 9.52% to 2300 CNY/ton due to reduced supply [18][21]. - Conversely, liquid gas prices plummeted by 78.03% to 29 CNY/ton, attributed to weak downstream demand [19][22]. Key Industry and Company News - The report emphasizes the importance of domestic substitution in high-end optical materials, suggesting a focus on companies like Stik and Dongcai Technology [4]. - It also highlights the animal nutrition sector, where the demand for amino acids is expected to grow, particularly for leading companies like Meihua Biological [4]. - The report suggests monitoring leading chemical companies that benefit from lower natural gas prices and recovering downstream demand, such as Wanhua Chemical [4].