Merger Arbitrage
Merger arbitrage is buying a takeover target after a deal is announced, when it trades a little below the offer price, to earn that spread if the deal closes. The main risk is the deal failing, which can send the price sharply lower.
When a company agrees to be bought, its shares usually trade a little below the offer price. Merger arbitrage buys those shares to earn the gap if the deal closes. The gain is small and slow, while a failed deal can cause a sharp drop.
- Category
- Trading Strategies
- Reading time
- 3 min
- Also called
- Risk arbitrage, Merger arb, Deal arbitrage
- Updated
Merger arbitrage in plain words
If a deal collapses, the target's shares can drop back towards where they traded before the announcement, causing a loss.1
The gap between the target's share price and the offer price is called the arbitrage spread.2
The main risk is that the deal falls through.2
How a merger arbitrage trade works
Spot the deal
Find an announced takeover with a clear offer price.
Measure the spread
Measure the spread: offer price minus the target's current price.2
Judge the risks
Check approvals, financing and timing; the primary risk is that of deal failure.2
Size for failure
Use Position Sizing that survives a broken deal.
Hedge if needed
For share deals, Hedging the buyer's stock may be used where allowed.
Check the rules
Short-selling and takeover rules differ by country.
Worked examples
Example 1 — Deal closes
Deal doneA hypothetical target trades at 48 against a 50 cash offer and the deal completes.
| Entry | 48 |
| Payout | 50 |
The arbitrage spread was captured when the deal closed.2
Example 2 — Deal fails
Deal brokeA hypothetical deal is blocked and the share falls from 48 to 36.
| Entry | 48 |
| After failure | 36 |
The deal failed and the shares slid back towards their pre-bid level, producing a loss.1
Example 3 — Risk vs reward
LopsidedA hypothetical trader compares a 2-point gain with a 12-point possible loss.
| Upside | +2 |
| Downside | −12 |
A failed deal usually costs far more than a completed one earns.2
Merger arbitrage vs buying shares
| Aspect | Merger arbitrage | Buying shares |
|---|---|---|
| Return source | Deal spread | Company growth |
| Upside | Capped near offer | Open-ended |
| Main risk | Deal failure | Business and market risk |
| Holding time | Until deal closes | Any |
Where merger arbitrage is used
Cash takeovers
Buying the target below the offer.
Share-swap deals
Using Hedging against the buyer's stock.
Event-driven funds
Spreading Exposure across many deals.
Portfolio mix
Adding returns with low Correlation to the market in calm times.
Advantages and disadvantages
Advantages
- Clear target price.
- Return linked to an event, not market direction.
- Many deals can be spread out.
Disadvantages
- Failed deals cause large losses.
- Gains are small and capped.
- Deals can take months.
- Approvals are hard to predict.
Going deeper
Read as far as you need. Each level builds on the one before it.
What it is
Beginner
The spread is the whole opportunity: the gap between market price and offer price.2
Not true arbitrage
Intermediate
Despite the name, this isn't true risk-free arbitrage.1
Lopsided payoff
Advanced
Losses from failed deals are typically much larger than gains from successful ones.2 Takeover rules differ by country.
Common mistakes
Ignoring deal risk
A blocked deal can erase many wins.
Oversizing
One failure can be large.
Forgetting time
A slow deal lowers the yearly return.
Skipping the terms
Cash and share deals behave differently.
Check your understanding
Test yourself before moving on. Each answer comes with an explanation.
Key points to remember
- Merger arbitrage buys takeover targets below the offer.
- The gap is the arbitrage spread.
- Deal failure is the main risk.
- Losses on failure can far exceed gains.
- Rules differ by country.
Frequently asked questions
Is merger arbitrage risk-free?
Why is the spread there?
Can retail traders do it?
Further learning
- Risk-to-Reward Ratio
Weighing small gains vs big losses.
- Position Sizing
Sizing for deal failure.
- Hedging
Hedging share deals.
- Exposure
Spreading deal risk.
Sources
This article is written in our own words. The sources below support the specific facts, rules and figures marked with a number in the text. Links open the original publisher’s page.
- Federal Reserve Bank of New York. Merger Options and Risk Arbitrage (Staff Report 761) (opens in a new tab) Checked .
- Journal of Finance (Mitchell and Pulvino). Characteristics of Risk and Return in Risk Arbitrage (opens in a new tab) Checked .
Educational content, not financial advice. Examples use hypothetical prices and simplified costs; actual fees, margin rules and regulations vary by broker, market and country. We are not affiliated with any publisher linked above. Last reviewed . Report an error or request a source credit.