On January 16, the phthalic anhydride market in Shandong region experienced fluctuating consolidation. The mainstream negotiated prices for o-xylene-based phthalic anhydride were 6,100–6,300 yuan/ton, while naphthalene-based phthalic anhydride was quoted at 5,700–6,050 yuan/ton. The price of raw material o-xylene fluctuated upward, while industrial naphthalene prices stabilized. The cost of phthalic anhydride increased, and downstream plasticizer prices rose amid fluctuations. Phthalic anhydride manufacturers ramped up equipment operations, maintaining stable operating rates. The phthalic anhydride market supply remained ample, and plasticizer enterprises maintained steady production loads. Demand for phthalic anhydride continued to provide support, with expectations of strong consolidation in the market outlook.