That’s a good point – successful by whose definition. In your example, Exxon considered the cultural integration a success because in the end Mobil was assimilated into their culture. However, it sounds like many Mobile people left because of it. I would consider the cultural takeover unsuccessful if: 1) Enough people left that there were additional unexpected costs from having to recruit a new talent and/or those that left took certain knowledge or skillsets with them that were critical to the achieving the expected synergies of the merger, or 2) Replacing the culture of the acquired company had a noticeable negative impact on outputs (e.g. product quality, service quality, process efficiencies, etc.) in such a way that the expected synergies/benefits of the merger were not realized.