Great question! I will answer the question based on the assumption that when you say ‘after M&A’, this is after integration has occurred. Therefore I would have the post mortem pivoting on the following questions and drilling down from here:
1. For any post mortem, it would be advisable to go back to the integration plan and measure/evaluate elements of the plan that worked and what didn’t work. Was the right framework established? Integration approach adequate for the elements being integrated? What aspects of the plan were missing? Were the right people involved?
2. If there were metrics established, a deeper dive on those that didn’t meet the targets should be discussed, and what proactive systems were in place or not in place to intervene will be a valuable lessons learned.
3. Last but not least is the trajectory of the performance. When the valuation was done, there were certain assumptions regarding potential synergies, market growth, revenue targets, etc. These are objective points of reference to evaluate whether or not the M&A is successful in realizing its initial objectives.