Activist investor Ancora Holdings has withdrawn its campaign against U.S. Steel, aligning with the proposed $14.9 billion acquisition by Japan's Nippon Steel. Ancora's decision comes as it noted 'apparent momentum' for the merger, which has garnered support from U.S. Steel shareholders. The shift in Ancora's stance is significant as it had previously sought to challenge the deal. The acquisition is closely monitored by the Trump administration, which is reportedly working to ensure investment security related to the transaction.