Reading an M&A Accretion/Dilution Model

Accretion/dilution analysis answers a narrow, specific question: after an acquisition closes, does the combined company's earnings per share go up or down relative to the acquirer's standalone EPS? It sounds like a simple arithmetic exercise, and mechanically it is, but the driver behind the answer is a genuinely useful piece of financial intuition once you see it clearly.

Building the pro forma numbers

Purchase Equity Value = Offer Price per Share × Target Shares Outstanding
Cash Consideration = Purchase Equity Value × % Cash
Stock Consideration = Purchase Equity Value − Cash Consideration
New Shares Issued = Stock Consideration ÷ Acquirer Share Price

The acquirer funds the deal with some mix of cash (often debt-funded) and its own stock. Each funding source has a real cost: cash funded by new debt costs the after-tax interest rate on that debt; stock costs the acquirer's own earnings yield, since issuing new shares dilutes existing shareholders' claim on the same earnings pool.

Pro forma net income and EPS

Pro Forma Net Income = Acquirer NI + Target NI + Pre-Tax Synergies × (1 − Tax Rate)
                        − (Cash Consideration × Cost of Debt) × (1 − Tax Rate)

Pro Forma EPS = Pro Forma Net Income ÷ (Acquirer Shares + New Shares Issued)

The combined net income adds both companies' standalone earnings, adds any real synergies (tax-effected, since synergies flow through the income statement like any other pre-tax item), and subtracts the after-tax cost of servicing any new debt raised to fund the cash portion. Note what's not in this formula: the equity issued to fund the stock portion has no interest cost, but it does show up on the other side of the ledger: in the denominator, as more shares outstanding.

The actual driver: earnings yield vs. cost of funding

Accretion / (Dilution) % = Pro Forma EPS ÷ (Acquirer NI ÷ Acquirer Shares) − 1

Here's the intuition that makes all of this click: a deal is accretive when the target's earnings yield (roughly Net Income ÷ Purchase Price, the inverse of the P/E multiple the acquirer paid) is higher than the acquirer's cost of the funding source used. If you're buying earnings more cheaply (in yield terms) than what it costs you to raise the money to buy them, EPS goes up. If you're overpaying relative to your funding cost, EPS goes down, even if the target is a perfectly good business.

This is why the same deal can be accretive funded one way and dilutive funded another. Debt is often "cheaper" in this narrow sense than issuing stock at a rich valuation, which is exactly why cash/debt-funded deals are more commonly accretive than stock-funded ones, holding the target and price constant.

Why cash/debt vs. stock is a real strategic choice, not just an accretion lever

Funding a deal with cash and debt is typically more accretive (when debt is cheap relative to the target's earnings yield) and avoids diluting existing shareholders' ownership percentage, but it increases leverage and financial risk, and requires actually having or being able to borrow the cash. Funding with stock conserves cash and effectively shares the deal's risk with the target's own shareholders, who become part-owners of the combined company (useful when the acquirer wants target management's continued alignment, or is uncertain about integration risk), but it dilutes existing shareholders and can be read by the market as a signal that the acquirer thinks its own stock is richly valued, which can pressure the acquirer's share price on announcement. Real deals frequently split the difference, using a mix of both to balance these tradeoffs rather than optimizing for accretion alone.

What "accretive" doesn't tell you

Accretion/dilution is a mechanical, near-term EPS effect. It says nothing directly about whether the deal creates real economic value, whether the strategic rationale is sound, or whether the synergy assumptions are realistic. A deal can be immediately accretive and still be a bad deal if the synergies never materialize or the acquirer overpays relative to the target's true long-run cash flow. Always ask, and always be ready to be asked yourself: is this accretion figure shown with or without synergies, and how confident should anyone be in those synergy numbers actually showing up?