The study analyzes the impact of voluntary synergy disclosures at the M&A announcement on M&A transactions in the European as well as in the US energy sector. Thereby, not only is the capital market perspective considered on both a long- and short-term horizon, but the operational point of view is also taken into account. The author shows, while utilizing the event study methodology, that capital markets attribute increased returns to those M&A transactions which expect synergy gains for both the US and European market. As the post-merger accounting study confirms the realization of these announced synergy gains, it may be inferred that capital markets do not overreact and management boards are not overconfident in realizing merger gains.weiterlesen