The thesis is an ex-post assessment of two horizontal mergers motivated by the dearth in post-merger analyses in the South African context. The objective is to examine whether market dynamics have changed as stated by the Competition Tribunal. The main theories tested are whether the merged firm post-merger was able to exert market power unilaterally or in coordinated manner. These constructs are examined against the ability of customers to restrain market power, barriers to entry, the effect of the remedies imposed and the financial performance.The results reveal that the Tribunal leans towards the SCP doctrine and demonstrates the need for a dynamic approach in competitive assessments informed by understanding how competitors and customers may react to a merger. The research findings indicate that the Tribunal’s conclusions on both the Nampak/Burcap and Scaw/Ozz transactions were unproven, post-merger. The research also demonstrates the need and importance of ex-post evaluations to improve future decisions on mergers.