Merger arbitrage is one of the most established event-driven investment strategies employed by hedge funds to generate returns from corporate transactions. By exploiting the price difference between a target company’s market value and the consideration offered by an acquirer, investors seek to capture deal spreads while carefully managing the risks associated with transaction completion. This report examines the mechanics of merger arbitrage and applies the framework to the proposed merger between Banca Monte dei Paschi di Siena (MPS) and Mediobanca, one of the most significant transactions in the Italian banking sector.

The analysis begins by explaining the foundations of merger arbitrage, including the distinction between cash and stock-for-stock transactions, the use of leverage, and the implementation of delta-neutral hedging strategies designed to isolate deal-specific returns from broader market movements. It also discusses the principal risks faced by arbitrage investors, including regulatory intervention, financing uncertainty, litigation, leverage, timing, and deal failure.

The report then examines the proposed acquisition of Mediobanca by Monte dei Paschi di Siena, highlighting the strategic rationale behind the transaction and the factors influencing market expectations of completion. Particular attention is given to shareholder alignment, the role of influential investors such as Delfin and Caltagirone, and the support of the Italian government, all of which contributed to a higher perceived probability of success. At the same time, regulatory scrutiny, governance concerns, and questions regarding the strategic logic of combining the two institutions remained important sources of uncertainty.

A detailed case study demonstrates how a merger arbitrage position can be constructed through a long position in Mediobanca shares combined with a short position in MPS shares based on the contractual exchange ratio. The report explains the rationale behind the entry and exit strategy, continuous hedge rebalancing, position sizing, and risk management techniques used to capture spread convergence while minimizing directional exposure to the Italian banking sector.

Finally, the report evaluates the outcome of the strategy, showing how successful spread convergence generated attractive risk-adjusted returns despite the asymmetric payoff profile inherent in merger arbitrage. It concludes that disciplined execution, rigorous analysis of deal fundamentals, and careful assessment of regulatory and stakeholder dynamics remain the key determinants of success in event-driven investing.