The tremendous growth of business and their impact on competition within the market raises concerns regarding the regulators ability to enforce fair competition and regulate large corporations. While Competition law strives to regulate the market through tangible punishment, its reactive nature might result in difficulties swiftly addressing anti competitive practices. This study explores the comparison of reactive and proactive regulatory enforcement measures on business compliance, by comparing Competition law with the new Digital Markets Act. The research, compiling of secondary sources, focuses on using compliance theories to explain the differences in ex post and ex ante enforcement measures and how firms might respond to the two. In the context of Competition law and the Digital Markets Act, we conclude that while big penalties could be a good deterrence, the reactive nature of Competition law has significant disadvantages compared to the proactive Digital Markets Act.