We analyze horizontal mergers when the acquirer holds a passive partial ownership stake (PPO) in the target firm prior to the merger. We show that a PPO reduces the minimal synergy level necessary to make a merger beneficial for consumers. It follows that an antitrust authority ignoring existing...

We examine the competitive effects of a passive partial ownership (PPO) when it serves as an instrument for the acquirer firm to learn the merger synergies with the target firm in advance. The realization of a synergy is uncertain ex ante, so that a direct merger exhibits a downside risk not...