Merger arbitrage

Merger arbitrage is a strategy of purchasing stocks of companies announced for acquisition at a discount to the deal price, betting that the deal will close and capturing the spread between the current trading price and the acquisition price. The arbitrageur assumes risk that the deal fails or is delayed.

How merger arbitrage works

The setup: Company ABC announces it will acquire Company XYZ for $100 per share. XYZ stock immediately rallies from $85 to $98 — near but not equal to the deal price. The $2 gap represents deal risk (the market is uncertain the deal will close).

The trade:

1. Buy the target. Purchase XYZ at $98.
2. Wait for closing. The deal requires regulatory approval, and that process takes 3–9 months.
3. Capture the spread. When the deal closes, XYZ is acquired and automatically converts to $100 cash per share.
4. Profit: $100 – $98 = $2 per share, or 2% return over the holding period.

For a 6-month holding period, a 2% return annualizes to ~4%.

Deal risk

The merger arbitrageur assumes risk that:

• Regulatory blocks the deal. Antitrust concerns may cause regulators (FTC, DOJ, foreign antitrust authorities) to block the deal.
• Financing fails. If the acquirer is using debt or equity financing, market conditions can prevent financing completion.
• Conditions are renegotiated. The acquirer may demand a lower price (reputational loss for the arbitrageur).
• Counterparty emerges. Another bidder may trigger a bidding war (good!) or kill the deal (bad).
• Delay. A deal expected to close in 6 months may take 12+, increasing the waiting cost.

When a deal is blocked, the target stock crashes (back to $85 or lower), causing significant losses for arbitrageurs.

Historical returns

Merger arbitrage has historically returned 5–10% annually with relatively low volatility. However, returns have compressed as more capital chases the same deals.

See also