This study assesses the heterogeneous impact of the death of Queen Elizabeth II on industry leaders in the United Kingdom. It reveals the firm-specific characteristics that lead to this heterogeneity. This study applies an event study methodology to a sample of 20 leading UK companies across a 250-day estimation window and a 40-day event window. According to the event study, the death of Queen Elizabeth II has had a differential impact on most UK companies for different industries. In contrast, companies in the Biotech, Oil & Gas, Mining, and Tobacco industries were less affected. However, companies in the Retail, Telecommunications, Banks, and Defense Contractors sectors show significant negative CARs. This article has implications for investors in identifying company sector-specific characteristics that drive premium returns and guiding diversification by improving the sectoral diversity of portfolios. However, the study is limited by a relatively small sample size. There is a gap in earlier research on the related change of kingship and stock market performance, and this study makes two contributions to the literature. The authors first analyze the impact of the death of Queen Elizabeth II on British firms. Secondly, the study also provides guidance on how investors can diversify across different sectors in the UK to reduce risk.