美国纸业和包装股盘前大跌，受关税和定价压力影响

Core Viewpoint - The stock prices of U.S. paper and packaging companies have significantly declined due to weak pricing and the U.S. Supreme Court's decision to reject most tariffs imposed by President Trump [1] Group 1: Company Impact - Packaging Corp. of America saw a decline of 5.6% in its stock price [1] - International Paper Company experienced a drop of 4.8% [1] - Smurfit WestRock's stock fell by 5.9% [1] - European competitor Mondi's stock decreased by 3.5% [1] Group 2: Industry Analysis - Analysts from Jefferies noted that prices for paper and cardboard are under pressure due to weak demand [1]