In plain English
A merger is one company buying another. Two questions decide whether it is a good idea: is the target worth the price, and does the combined company earn more per share afterwards? The first is valuation. The second is accretion/dilution — a mechanical check on whether earnings per share go up or down once you pay for the deal.
The advanced view
Accretion/dilution is a financing test, not a value test: paying with cheap debt against a low-multiple target is accretive even when the deal destroys value. Value creation requires the present value of synergies to exceed the control premium paid. The two tests answer different questions and a credible answer states both.
Start with the price. The offer is made for equity, but you acquire the whole capital structure, so the purchase enterprise value is the offer equity value plus assumed net debt. On top of the target's unaffected share price sits a control premium — typically 20-40% in public deals — which is the buyer's payment for the right to direct the assets. Everything the buyer hopes to earn back sits in synergies and in better management of the same assets.
Synergies come in two families and they are not equally credible. Cost synergies (overlapping head office, procurement scale, plant consolidation, IT rationalisation) are specific, controllable and land within 12-24 months, so a diligence team can underwrite them. Revenue synergies (cross-selling, wider distribution, pricing power) require customers to behave, arrive later and are routinely overestimated. Always phase them: a synergy worth 100 a year, ramping 30/70/100 over three years with one-off integration costs of 1.5x the annual run-rate, is worth far less than 100/WACC.
Deal arithmetic
Purchase EV = Offer equity value + Net debt assumed Control premium = Offer price / Unaffected price − 1 Pro-forma NI = NI_acq + NI_tgt + Synergies×(1−t) − After-tax new interest − Incremental D&A Pro-forma EPS = Pro-forma NI / (Shares_acq + New shares issued) Accretive if Pro-forma EPS > Standalone EPS_acq All-stock rule of thumb: accretive when P/E_acquirer > P/E_target (pre-synergy) Cash deal breakeven: after-tax cost of debt < Target earnings yield (E/P) PV of synergies = Σ [Phased synergy_t ×(1−t) / (1+WACC)^t] − Integration cost
Worked example: accretion/dilution on a cash deal
Step 1 of 11
- 1Acquirer: net income 500, shares 250 → standalone EPS =
Consideration structure carries the risk-sharing message. Cash is certain, uses balance-sheet capacity and signals that the acquirer believes its own shares are undervalued. Stock shares both upside and downside with target holders and signals the opposite, which is why acquirer shares usually fall on announcement of an all-stock deal. Fixed exchange ratios pass market risk to the seller; fixed value passes it to the buyer. Earn-outs bridge disagreement about the target's forecast, and contingent value rights do the same for a specific event such as a trial result.
Diligence and defences
Commercial diligence
Market size and growth, customer concentration, win/loss rates, pricing power, pipeline quality. The consultant's workstream in most deals.
Financial diligence
Quality of earnings: normalise EBITDA for one-offs, check working-capital seasonality, verify the cash conversion and the net-debt bridge at close.
Operational diligence
Capacity, footprint, systems, procurement and the true cost and timeline of realising cost synergies.
Poison pill
Rights plan letting existing holders buy shares cheaply once a raider crosses a threshold, diluting the bidder.
White knight / squire
A friendlier buyer, or a minority stake sold to a friendly holder, to block a hostile bid.
Staggered board
Directors elected in classes so a bidder cannot replace the board in one meeting; the strongest structural defence.
Merger arbitrage is the market's own probability estimate of a deal closing. If a target trades at 92 against a 100 cash offer expected to close in six months, the spread compensates for deal risk: regulatory blocks, financing failure, a shareholder vote, or a material adverse change. Implied probability ≈ (Current − Standalone) / (Offer − Standalone). Quoting that number turns a qualitative 'will it close?' into a number the interviewer can argue with.
Must know cold
- ✓Purchase EV = offer equity + net debt; you buy the whole capital structure.
- ✓Cash deal: accretive when the target's earnings yield beats the after-tax cost of debt.
- ✓All-stock deal: accretive when the acquirer's P/E is higher than the target's.
- ✓Accretion is not value creation; only synergies above the premium create value.
- ✓Cost synergies are underwritable, revenue synergies are a hope — phase and haircut them.
- ✓Goodwill = purchase price − fair value of identifiable net assets; it is tested for impairment, not amortised under IFRS.
Common pitfalls
- ×Adding full run-rate synergies in year one and ignoring the integration cost.
- ×Forgetting the tax shield: new interest and synergies both hit after tax.
- ×Comparing the offer to today's price rather than the unaffected pre-rumour price.
- ×Treating an accretive deal as a good deal when the premium exceeds synergy value.
- ×Ignoring the step-up in D&A from purchase price allocation in an asset deal.
Essential vocabulary
- Accretion / dilution
- Whether pro-forma EPS rises or falls versus the acquirer's standalone EPS.
- Control premium
- Percentage paid above the unaffected share price for the right to control the business.
- Purchase price allocation
- Assigning the price to identifiable assets at fair value, with the residual booked as goodwill.
- Exchange ratio
- Acquirer shares issued per target share in a stock deal; fixed ratio or fixed value.
- Earn-out
- Deferred consideration paid only if the target hits agreed post-close targets.
- Deal spread
- Gap between the offer price and the traded price, compensating for the risk the deal breaks.
Strategy connection
Buy versus build is the same NPV question with different risk. Acquisition buys time and removes a competitor at the cost of a premium and integration risk; organic build is cheaper per unit of capacity but slower and may arrive after the window closes. State the strategic logic first — scale, capability, market access, consolidation — then let the arithmetic test whether the price still works.
Exercises
Try each one on paper before revealing the worked solution.
Exercise 1
Acquirer P/E is 18x with net income 400 and 200 shares. It buys a target earning 90 for 1,350 in an all-stock deal at its own share price. Is it accretive, and by how much?
Exercise 2
Cost synergies of 100 phase in 40/80/100% over three years, integration costs are 120 in year one, tax is 25% and WACC is 9% with the synergy perpetual after year three. Value the synergies.
Exercise 3
Structuring exercise: a client asks 'should we buy our largest distributor?'. Structure the answer before any arithmetic.