BAE Systems shares dropped 1.73% to 1,878p Monday in London, bucking gains in European markets as the STOXX 600 hit a record. The decline came despite UK and Japan accelerating work on the GCAP fighter jet program, which involves BAE. The company holds an order backlog of £83.6 billion and kept its 2026 outlook unchanged in May. Valuation concerns persist, with the stock trading at a P/E of 28.10.