---
description: "Captures excess returns from merger arbitrage (M&A) by taking long positions in target company stock and, for stock mergers, short positions in the acquirer, exploiting the spread between current and deal prices."
tags: [stocks, event-driven, merger-arbitrage, risk-arbitrage]
---

# Event-Driven — M&A

**Section**: 3.16 | **Asset Class**: Stocks | **Type**: Event-Driven / Arbitrage

## Overview
This strategy, also known as "merger arbitrage" or "risk arbitrage", attempts to capture excess returns generated via corporate actions such as mergers and acquisitions (M&A). When one publicly traded company announces the acquisition of another, a spread typically exists between the target's current market price and the proposed deal price. The trader seeks to profit from this spread closing at deal completion.

## Construction / Signal
A merger arbitrage opportunity arises when a publicly traded acquirer announces intent to buy a publicly traded target at a price differing from the target's current market price. Two main transaction types:

**Cash merger**:
- Trader establishes a **long position in the target company stock** only.
- Profit = (deal price − current target price) if the deal closes.

**Stock merger**:
- Acquirer offers N_B shares of acquirer stock B for each share of target stock A.
- Trader **buys 1 share of target A** and **shorts N_B shares of acquirer B**.
- Example: Current price of A = $67, current price of B = $35, exchange ratio = 2 shares of B per share of A.
  - Initial net credit = 2 × $35 − $67 = $3 per share of A bought.
  - This $3 is the profit if the deal closes.
  - If the deal falls through, the trader will likely lose money.

## Entry / Exit Rules
- **Entry**: After public announcement of a merger/acquisition deal, establish the arbitrage position (long target, short acquirer for stock mergers).
- **Exit — deal closes**: Positions are settled at deal terms; long position in target delivers the deal price; the profit is locked in.
- **Exit — deal breaks**: Close positions at market prices; the spread typically widens sharply on deal failure, resulting in a loss.
- **Stop-loss**: Discretionary; deal-break risk is the primary risk.

## Key Parameters
- **Deal spread**: Difference between current target price and proposed deal price (or equivalent in stock merger terms)
- **Exchange ratio (stock mergers)**: Number of acquirer shares per target share
- **Merger type**: Cash vs. stock merger (determines position structure)
- **Holding period**: Duration from announcement to deal close (weeks to months)

## Variations
- **Long-only (cash merger)**: Buy target only; no short leg.
- **Dollar-neutral (stock merger)**: Long target, short acquirer in ratio given by deal terms.
- **Index of deals**: Construct a diversified portfolio across multiple live merger situations simultaneously to reduce single-deal risk.

## Notes
- The primary risk is "deal break risk": if the merger falls through (regulatory rejection, board change, financing failure), the trader typically suffers a loss as the target price drops back toward pre-announcement levels.
- Expected return = (spread × probability of deal close) − (loss on deal break × probability of break).
- Transaction costs and financing costs for short positions reduce profitability.
- Holding period depends on deal timeline: typically weeks to several months.
- This strategy requires monitoring deal-specific news (regulatory filings, shareholder votes, competing bids).