Copper prices plummeted nearly 20% following President Trump's decision to exclude refined copper from new tariffs set to take effect August 1. This policy change halted a months-long rally and shifted the market dynamics, impacting domestic and global prices. Shares of major copper producers declined sharply as traders reacted to the tariff reversal. The move exempted input materials like cathodes and anodes, causing a significant drop in copper futures and erasing the previous domestic price premium.