The aim of the paper was to do diachronic linguistic research in Corporate English by doing a lexical analysis of American and British annual reports for fiscal years 2002 and 2021. Corporations, as entities of creative disruption, stay at the heart of capitalism and act as the engine of technological development in the world. However, the language of their communication with their owners (shareholders) and other stakeholders interested in their performance, such as employees, suppliers, lenders, and prospective owners, has not been empirically analysed. The article provides the results of diachronic corpus-based research of multi-word expressions (MWEs) in Corporate English. The annual reports of ten American and ten British corporations for fiscal years 2001 and 2021 were analysed separately to get information about the lexical changes that occurred in these financial documents in two variants of English over two decades. The results of the research revealed both differences and diachronic changes at the lexical level in American and British Corporate English and the same can be used in BE classes to make BE students aware of two varieties of English by presenting and practicing real empirically proved vocabulary. The results of the research can be used in BE classes in a variety of ways, bearing in mind that BE students, to communicate effectively, should be exposed to the newest vocabulary used in the business world.