Title: M&A activity and the macroeconomic environment - a quantitative study on the impact of the macroeconomic environment on aggregate merger and acquisition activity in the US Background: There is a lack of established theories on what drives M&A activity. A subject that has received much attention in literature but produced few compelling results. The full explanation of the dynamics of aggregate M&A activity has yet to be captured. An explanation which could provide useful insights for central banks, corporate managers and any other parties affected by this prominent feature of the US economy which have come to shape and dominate the corporate landscape. Purpose: The purpose of this thesis is to investigate the relationship between the dynamics of aggregate M&A activity and macroeconomic variables representing the state of the economy in the US. Method: The methodology that is used in the thesis is based on a deductive research approach with a quantitative research design. In addition, the thesis has also made use of a longitudinal panel research. The thesis hypotheses have been formulated using earlier research and existing theories about the subject of mergers and acquisitions as well as macroeconomic factors. Further on, the data set that has been analyzed consisted of 73137 transactions during the time period January 1, 1980 - January 1, 2020. Conclusion: The study finds that there are signs of relationships between macroeconomic variables and aggregate M&A activity, although the precise characteristics of these relationships has not been established. The result of the study indicates that the macroeconomic environment as a whole affects aggregate M&A activity and that it can be an important part of the explanation for the dynamics of aggregate M&A activity. It cannot be established that macroeconomic variables can be used to predict M&A activity, however there are interesting indications suggesting this might be the case.