The contemporary business environment has been highly complex and dynamic with organizations facing unprecedented amount of competition due to globalization and technological innovations. Merger and acquisition is one of the most popular organization strategy that organizations apply when faced with this kind of operating environment acquiring resources, skills, and competencies beyond their organization control. Many studies have been done to support implementation of M&As within organizations but they have indicated conflicting outcomes with some showing that it negatively affect organization performance and others indicating they positively affect performance. However, none of the studies done has concentrated on the effect within the privately traded organizations and very few but conflicting studies have been done on this relationship in Kenya. This study therefore sought to assess the effects of merger and acquisition on the performance of privately trading organizations in Kenya. The study was grounded upon the efficiency theory, the market power theory, and economic production theory. Reviewed literature revealed existing gaps related to the literature. The study adopted descriptive research design on short run data collected at UAP Insurance within the pre-merger (2012-2014) and post-merger (2015-2017) periods for various performance statistics, where descriptive analysis was applied to assess the differences and independent sample t-test. The study found that M&A affects the net profit margin, Return on Assets, Return on Equity, and earnings per share with all these performance indicators showing that the post-merger period had poorer performance than the pre-merger period. The study further observed that the M&A implementation caused serious disruptions in the operating environment and organization culture of the organization, which was bound to have negative implications on organization performance, employees and shareholders. The study recommends that organizations should avoid M&A strategy unless their current assets are able to fund their current liabilities beyond the short run period, as the declined performance was linked to the disruptions experienced from M&A implementations. The study also recommends that M&A intended changes should occur sequentially to cushion the organization internal operations from the disruptions due to the changes. Study suggests further studies assessing the long term impact of M&A on organization performance.