Accretion / dilution

Key takeaways

Accretive = EPS goes up post-deal. Dilutive = EPS goes down. Public-company boards react sharply to dilutive deals; CFOs structure deals to be accretive.
Three things determine accretion: target's earnings yield (1 / P/E) vs acquirer's, financing mix (cash / debt / stock), and synergies.
Quick rule for an all-stock deal: accretive if target's P/E < acquirer's P/E. Inverse for dilutive.
Cash-financed deals are accretive whenever after-tax cost of debt is below target's earnings yield. With rates at 5%+, harder to clear that bar than in the ZIRP era.
Don't confuse "accretive" with "good." Accretive deals can destroy value if the target is overpaid; dilutive deals can create value if synergies materialise. EPS impact is one lens, not the only one.

The math

Accretion / dilution is the percentage change in pro forma EPS vs the acquirer's standalone EPS:

Accretion / Dilution % = (Pro Forma EPS − Standalone EPS) / Standalone EPS

Pro Forma EPS = (Acquirer Net Income + Target Net Income + After-tax Synergies − Incremental Interest after tax) / Pro Forma Diluted Shares

The numerator combines the two companies' earnings, adds expected synergies (after tax), and subtracts the interest cost of any new debt used to finance the deal. The denominator is the pro forma share count — the acquirer's existing shares plus any new shares issued for the deal.

The three drivers

Target's earnings yield vs acquirer's

Target's earnings yield = 1 / target P/E. If the acquirer pays 20× P/E for a target that's earning at a 5% yield, but the acquirer's own stock trades at 25× (4% yield), the target is "cheaper" on an earnings basis — accretive in stock-funded deals before any synergy.

Financing mix

Three ways to finance a deal:

Cash — most accretive. Acquirer's existing cash earns ~0–4% (treasury yield); target's earnings come in at the target's earnings yield. Substituting target earnings for cash interest is almost always accretive.
Debt — accretive if after-tax cost of debt is below target's earnings yield. With BBB-rated debt at ~5–6% pre-tax (3.5–4% after tax), and target earnings yields often 5–8%, deals usually clear. Less reliable in higher-rate environments.
Stock — accretive if target P/E is below acquirer P/E. Otherwise dilutive.

Synergies

The wildcard. Cost synergies (overlapping HQ, redundant systems, vendor consolidation) are usually credible. Revenue synergies (cross-sell) are harder to underwrite; banks routinely apply 25–50% probability haircuts.

Synergies hit the EPS calculation post-tax. If you announce $100M of pre-tax synergies at a 25% tax rate, $75M flows to the EPS calculation. Phasing matters too: if synergies ramp over 3 years, the year-1 accretion is much smaller than the run-rate accretion.

Worked example — three financing scenarios

Acquirer: $500M net income, 100M diluted shares, $5.00 EPS, $25 share price (5× P/E... let's say $50, 10× P/E for realism). Stock at $50, P/E = 10×.

Target: $50M net income, $500M offer (10× P/E on target as well). $150M of expected pre-tax synergies, fully phased in by year 2. Tax rate 25%.

Scenario	Mechanics	Year-2 pro forma EPS	vs $5.00 standalone
All cash	$500M cash at 4% pre-tax foregone interest = $20M pre-tax = $15M after-tax. Net income gain = 50 + (150 × 0.75) − 15 = $147.5M. Shares 100M.	$6.48	+29.5% accretive
All debt at 6% pre-tax	$500M debt × 6% = $30M interest pre-tax = $22.5M after-tax. Net income gain = 50 + 112.5 − 22.5 = $140M. Shares 100M.	$6.40	+28.0% accretive
All stock	$500M / $50 = 10M new shares issued. Net income gain = 50 + 112.5 = $162.5M. Shares 110M.	$6.02	+20.5% accretive

All three are accretive thanks to synergies. The cash and debt versions are most accretive; stock is most dilutive (more shares to share the earnings across) but still positive. Without synergies, the stock-financed deal at 10× × 10× would be EPS-neutral, debt-financed would be modestly accretive, cash would be strongly accretive — illustrating why CFOs prefer cash when it's available.

The honest limits of accretion / dilution

It says nothing about value creation. An acquirer can do an accretive deal that destroys NPV — paying 30× for a target that's worth 10× is dilutive on intrinsic value even if accretive on first-year EPS.
Synergies can be aspirational. Sponsor-side and acquirer-side analyses both tend to overstate revenue synergies. Stress-test at 50% of management's case.
Year-1 vs run-rate matters. A deal that's mildly dilutive in year 1 but strongly accretive at run-rate is fine; the market generally tolerates the J-curve. A deal that's dilutive at run-rate is structurally bad.
Accounting choices distort EPS. Purchase accounting amortisation, deferred-revenue write-downs, and stock comp adjustments all hit reported EPS. Adjusted (cash) EPS is usually a cleaner metric for the analysis — quote both.

Sense checks

Question	If the answer is...
Year-1 accretion	>10%: usually a clear "yes" for the board. 0–5%: marginal — deal needs strategic logic. Negative: tough sell to public shareholders.
Run-rate accretion (year 3+)	>15% with reasonable synergies: strong deal. <5%: synergies aren't enough to justify the price.
Without synergies	Still accretive: financially attractive on its own. Dilutive: deal logic must rest on synergies — which are riskier.
Pro forma leverage	Stays under 4× total debt / EBITDA: bond-rating-friendly. Above 5×: rating downgrade risk; investment-grade acquirers often won't go there.

Common errors

After-tax synergies forgotten. Synergies are pre-tax dollars; the bottom-line impact is post-tax. Apply the acquirer's tax rate.
Phasing not modelled. Run-rate synergies in year 1 are unrealistic. Phase over 2–3 years.
Foregone interest on cash missed. If the acquirer uses $1B of cash, that cash was earning interest. Subtract the foregone after-tax interest.
New share count missed for stock deals. Pro forma EPS denominator must include new shares issued. Easy to forget when running the analysis quickly.
Reporting only year-1. Year-1 accretion can be misleading if synergies are back-end loaded. Always show year 1, year 3, and run-rate.

How Smalt AI builds it

Tell your AI coworker the target, the offer terms, and the financing mix — "accretion-dilution on Acquirer buying Target at $42/share, 50% cash 50% stock, $100M synergies phased over 3 years." What you get:

A model with the full pro forma EPS bridge for years 1, 2, 3, and run-rate.
Three financing scenarios (cash, debt, stock) shown side-by-side, with the deal's actual mix highlighted.
Synergy phasing modelled explicitly — pre-tax, after-tax, with a sensitivity row on synergy realisation (50% / 75% / 100% of management's case).
Pro forma leverage and credit metrics tracked alongside, with rating-downgrade thresholds flagged.
An "if zero synergies" view to test how robust the deal logic is.
Standard institutional formatting — green if accretive, red if dilutive, source comments on every input.