Mergers and acquisitions is the bread and butter of investment banking. M&A advisory is what most people picture when they think of IB – advising companies on buying, selling, or merging with other businesses. If you understand M&A, you understand what investment bankers actually do day-to-day.
This guide covers everything you need to know about M&A for your interviews. No textbook padding – just the concepts that get tested.
Why Companies Do M&A
Every deal needs a rationale, and interviewers will expect you to understand the main drivers:
Revenue Synergies: The combined company can generate more revenue than both could separately. Cross-selling products, entering new markets, gaining access to a new customer base. Revenue synergies are harder to achieve and banks typically discount them more heavily.
Cost Synergies: Eliminating duplicate functions – two HR departments become one, overlapping offices close, redundant technology platforms get consolidated. Cost synergies are more concrete and easier to model, which is why banks and investors give them more weight.
Strategic Rationale: Acquiring a competitor to gain market share, buying a company for its technology or intellectual property, vertical integration (buying a supplier or distributor), or diversifying into adjacent markets.
Financial Engineering: In leveraged buyouts, the acquirer uses debt to amplify equity returns. The company itself may not change, but the financial structure creates value for the buyer.
When asked 'give me an example of a good M&A deal', structure your answer: who bought whom, what was the strategic rationale, what was the valuation, and what synergies were expected. Have one recent deal prepared.
Types of Mergers
Horizontal: Two companies in the same industry at the same stage. Competitor buying a competitor. Example: two pharmaceutical companies merging. Biggest source of cost synergies.
Vertical: Buying a company in your supply chain – a manufacturer buying a distributor, or a retailer buying a supplier. Reduces costs, secures supply, captures more margin.
Conglomerate: Companies in completely different industries merging. Less common now because investors can diversify themselves. The rationale usually needs to be very specific.
The M&A Process: Buy-Side vs Sell-Side
Sell-Side (Most Common for Banks)
The bank advises a company that wants to sell itself or a division. The process typically takes 6–12 months:
The bank prepares marketing materials (teaser, CIM/information memorandum), identifies and contacts potential buyers, manages the data room and due diligence process, runs a competitive auction to maximise the sale price, negotiates deal terms, and helps close the transaction. The bank earns an advisory fee, typically 1–2% of the transaction value.
Buy-Side
The bank advises a company that wants to acquire a target. The bank helps identify targets, performs valuation analysis, structures the offer, arranges financing (if needed), and negotiates on behalf of the buyer. Buy-side mandates can also involve fairness opinions – where the bank gives a formal opinion on whether the price being paid is fair to shareholders.
'Walk me through a sell-side M&A process' is a common question. Hit the key stages in order: engagement letter, preparation of marketing materials, buyer outreach, first round bids, management presentations, due diligence, final bids, negotiation, signing and closing.
Deal Structure: Cash vs Stock vs Mixed
All-Cash: Acquirer pays cash for each share of the target. Clean and simple. Shareholders get immediate liquidity. Acquirer may need to raise debt to fund it.
All-Stock: Acquirer issues new shares to target shareholders in exchange for their shares. No cash leaves the door, but existing shareholders get diluted. Accretion/dilution analysis matters most here.
Mixed: Combination of cash and stock. Most large deals use a mix. The split affects accretion/dilution, financing costs, and risk-sharing between buyer and seller.
The choice of consideration depends on the acquirer's cash position, how expensive its stock is (if the acquirer thinks its stock is overvalued, stock deals are attractive), tax implications, and what the target's shareholders prefer.
Accretion and Dilution: The Quick Version
When a company acquires another, the key question is: does the combined company's Earnings Per Share (EPS) go up (accretive) or down (dilutive)?
Quick test for all-stock deals: If the target's P/E ratio is lower than the acquirer's P/E ratio, the deal is likely accretive. You're buying 'cheaper' earnings. If the target's P/E is higher, it's likely dilutive. There's a dedicated blog going deeper on this.
Synergies: How They're Valued
Synergies are the additional value created by combining two companies. Banks quantify them and include them in the deal model:
Cost synergies: Typically modelled as a percentage of the target's or combined company's cost base. Headcount reductions, facility closures, system consolidation. Often phased in over 1–3 years. Banks apply a multiple to the fully realised annual synergy value.
Revenue synergies: Harder to quantify and typically valued at a lower multiple than cost synergies because they're less certain. Cross-selling, new market access, pricing power.
A deal might be dilutive before synergies but accretive after synergies are included. This is a common interview nuance.
Hostile vs Friendly Deals
Friendly: Target's board agrees to the deal and recommends it to shareholders. This is the normal process.
Hostile: The acquirer goes directly to shareholders (tender offer) or tries to replace the board (proxy fight) because the target's board has rejected the offer.
Defence mechanisms you should know:
- Poison Pill: If any shareholder acquires more than a threshold (e.g., 15%) of shares, all other shareholders can buy additional shares at a discount, massively diluting the hostile bidder.
- White Knight: The target finds a friendlier acquirer to make a competing bid.
- Pac-Man Defence: The target makes a counter-bid for the acquirer. Rare but dramatic.
- Crown Jewel Defence: The target sells off its most valuable assets to make itself less attractive.
- Staggered Board: Only a fraction of board seats are up for election each year, making it harder for a hostile bidder to gain board control quickly.
Common M&A Interview Questions
Q: Why would a company acquire another company? A: Synergies (cost and revenue), strategic positioning, market share, technology acquisition, vertical integration, financial engineering, or to eliminate a competitor.
Q: Walk me through a sell-side M&A process. A: Engagement → marketing materials → buyer outreach → first round bids → management presentations → due diligence → final bids → negotiation → signing → closing.
Q: What's the difference between an asset deal and a stock deal? A: In a stock deal, the buyer acquires shares and takes on all assets and liabilities. In an asset deal, the buyer selects specific assets and liabilities. Asset deals are more complex but allow cherry-picking.
Q: How do you determine the offer price? A: Combination of valuation analysis (DCF, comps, precedents), synergy analysis, precedent premiums paid, and negotiation. The offer typically includes a 20–40% premium to the target's current share price.
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