The study is devoted to a comparative analysis of the global and domestic experience of integrating business structures in conditions of competition and institutional heterogeneity. The aim is to identify the mechanisms through which integration transactions transform operational efficiency and value creation, as well as to determine the role of the institutional environment in the variability of results. The questions relate to the impact of the industry, the type of transaction and the development of the corporate control market on the dynamics of revenue and profitability. The relevance is due to the significant contribution of M&A to growth strategies and the need to adapt best practices to the Russian context. The novelty lies in the IMRAD description, which links financial metrics with institutional factors. The materials and methods include a longitudinal analysis of public companies in the United States, the EU, and Russia from IT, industry, and retail that completed major transactions in 2010-2022. Time series analysis, correlation and regression modeling, comparative analysis of averages, as well as content analysis of corporate reports and business press are applied. Indicators: revenue growth rates, return on equity (ROE), market share change and estimated synergy coefficient; dynamics were estimated over a three-year post-integration horizon. For the institutional cross-section, the share of hostile takeovers was used as an indicator of the development of the corporate control market. Triangulation of the data provided verification of the conclusions. The results capture the superiority of the American model: maximum growth in IT, a pronounced J-shaped ROE profile with rapid excess of the pre-integration level, and the highest synergy coefficient.; In the EU, the indicators are moderate and balanced, in Russia they are minimal, especially in industry. The share of hostile takeovers is higher in the United States and is decreasing; in Russia it remains low, although it is growing, which indicates the maturation of the corporate control market. The correlations between integration and profitability growth are stronger in the United States and weaker in Russia; inter-regional gaps are not narrowing. The discussion interprets the differences through the prism of institutions: protection of shareholders' rights, transparency, market control discipline and the quality of post-integration management determine the realization of synergy. Practical findings include the development of independent corporate oversight, standardization of integration processes, increased accountability, and incentives for management for long-term value. The limitations are related to self-reporting and industry sampling; the prospects are causal modeling, panel expansion, and regulatory scenario analysis. The contribution is a framework for comparing M&A results in institutionally different jurisdictions.