Accretion/Dilution Analysis: Step-by-Step Guide for IB Interviews

What Is Accretion/Dilution Analysis?

Accretion/dilution analysis is the cornerstone of M&A analysis in investment banking. It answers one critical question: after an acquisition closes, will the acquirer's earnings per share (EPS) go up (accretive) or down (dilutive)?

This matters because public company CEOs and boards care deeply about EPS. A dilutive deal -- one that reduces EPS -- faces scrutiny from shareholders and analysts. An accretive deal is easier to justify. While accretion/dilution is not the sole factor in deal decisions, it is always part of the conversation, and it is one of the most heavily tested topics in IB interviews.

This guide walks through the full analysis step by step, provides a mental math shortcut for quick calculations, and covers the most common interview questions. For the broader context of how this fits into deal analysis, see our guides on merger models and valuation methods.

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The Core Concept

Accretion and dilution are defined relative to the acquirer's standalone EPS:

• Accretive: Pro forma EPS (combined company) > Acquirer's standalone EPS. The deal increases earnings per share.
• Dilutive: Pro forma EPS (combined company) < Acquirer's standalone EPS. The deal decreases earnings per share.

The intuition is straightforward. When you buy a company, you gain its earnings. But you also pay for it -- either with cash (which has an opportunity cost or financing cost) or with stock (which increases your share count). The question is whether the earnings you gain outweigh the cost you incur.

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Step-by-Step Walkthrough

Let us build an accretion/dilution analysis from scratch with a concrete example.

The Setup

• Acquirer (Company A): Share price $50, 100 million shares outstanding, net income $500 million, EPS = $5.00, P/E ratio = 10.0x
• Target (Company B): Share price $30, 50 million shares outstanding, net income $200 million, EPS = $4.00, P/E ratio = 7.5x
• Offer price: $40 per share (a 33% premium to Company B's current price)
• Deal structure: 100% stock deal
• Expected synergies: $50 million pre-tax ($37.5 million after-tax at a 25% tax rate)

Step 1: Calculate the Purchase Price

Total equity purchase price = Offer price x Target shares outstanding

$40 x 50 million shares = $2.0 billion

Step 2: Determine New Shares Issued (Stock Deal)

In a stock deal, the acquirer issues new shares to the target's shareholders. The exchange ratio determines how many:

Exchange ratio = Offer price / Acquirer share price = $40 / $50 = 0.80x

New shares issued = Exchange ratio x Target shares outstanding = 0.80 x 50 million = 40 million new shares

Step 3: Calculate Pro Forma Shares Outstanding

Pro forma shares = Acquirer shares + New shares issued

100 million + 40 million = 140 million shares

Step 4: Calculate Pro Forma Net Income

Pro forma net income = Acquirer net income + Target net income + After-tax synergies - After-tax incremental costs

For now, assume no incremental costs beyond what we have:

$500M + $200M + $37.5M = $737.5M

In practice, you would also adjust for:

• Foregone interest income on cash used (in a cash deal)
• New interest expense on acquisition debt (in a debt-financed deal)
• Incremental D&A from purchase price allocation (writing up assets and creating goodwill)
• Deal-related amortization (amortization of intangible assets like customer relationships, trade names, etc.)

Let us add one adjustment: assume $30 million in incremental amortization of intangible assets from purchase accounting (non-cash, but it reduces pre-tax income). After-tax impact: $30M x (1 - 25%) = $22.5M reduction.

Adjusted pro forma net income = $737.5M - $22.5M = $715M

Step 5: Calculate Pro Forma EPS

Pro forma EPS = Pro forma net income / Pro forma shares outstanding

$715M / 140M = $5.11

Step 6: Determine Accretion or Dilution

Acquirer standalone EPS = $5.00 Pro forma EPS = $5.11

Accretion = $5.11 - $5.00 = $0.11 per share, or +2.1%

The deal is accretive. The acquirer's shareholders end up with higher EPS after the deal.

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Why This Deal Is Accretive

The key driver of accretion/dilution in a stock deal is the relative P/E ratios. Here is the rule:

• If the acquirer's P/E is higher than the target's effective P/E (price paid / EPS), the deal tends to be accretive.
• If the acquirer's P/E is lower than the target's effective P/E, the deal tends to be dilutive.

In our example:

• Acquirer P/E = 10.0x
• Target effective P/E = $40 offer price / $4.00 EPS = 10.0x

These are roughly equal, so the deal is approximately neutral before synergies. The synergies push it into accretive territory.

If the acquirer had a P/E of 8.0x and was paying 10.0x for the target, the deal would likely be dilutive (even with modest synergies) because the acquirer is "overpaying" in P/E terms.

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The Mental Math Shortcut

In interviews, you may be asked to quickly determine whether a deal is accretive or dilutive without building a full model. Here is the shortcut:

For an All-Stock Deal

1. Compare the acquirer's P/E to the price paid for the target expressed as a P/E.
2. Acquirer P/E > Target effective P/E = Accretive
3. Acquirer P/E < Target effective P/E = Dilutive
4. Add synergies -- they always push toward accretion.

For an All-Cash Deal

1. Calculate the after-tax cost of cash. If the acquirer uses cash on balance sheet, the cost is the foregone after-tax interest income. If the acquirer borrows, the cost is the after-tax interest expense.
2. Compare that cost to the target's earnings yield (EPS / price paid, or the inverse of the P/E).
3. Target earnings yield > After-tax cost of cash = Accretive
4. Target earnings yield < After-tax cost of cash = Dilutive

Example: Acquirer borrows at 6% pre-tax (4.5% after-tax at 25% tax rate) to buy a target at 10x P/E (10% earnings yield). Since 10% > 4.5%, the deal is accretive. The earnings you gain exceed the interest cost.

For a Mixed Deal (Cash + Stock)

Weight the accretion/dilution from each component. The cash portion follows the cash logic; the stock portion follows the P/E comparison logic. Or simply build the full analysis -- mixed deals are harder to shortcut.

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Key Adjustments That Affect the Analysis

Several technical adjustments can significantly swing the accretion/dilution result. Interviewers often test these.

Purchase Price Allocation and Amortization

When an acquirer pays more than the target's book value of equity (which is almost always), the excess is allocated to identifiable intangible assets (customer relationships, technology, trade names) and goodwill. The intangible assets are amortized over their useful lives, creating a non-cash expense that reduces pro forma net income.

This amortization is a real drag on reported EPS. Some analysts run the accretion/dilution analysis both with and without this amortization to show the "cash EPS" impact.

Synergies

Synergies are a major driver of accretion. They come in two forms:

• Cost synergies: Headcount reductions, facility consolidations, technology system savings. These are more predictable and typically realized within 1-2 years.
• Revenue synergies: Cross-selling opportunities, pricing power, market expansion. These are harder to achieve and often discounted heavily by the market.

In the accretion/dilution analysis, synergies are added to pro forma net income (after-tax). A deal that is dilutive before synergies may become accretive once synergies are factored in -- this is often the argument acquirers make to justify paying a high premium.

Financing Costs

How the deal is funded directly impacts accretion/dilution:

• All-cash (from balance sheet): Lost interest income on the cash used. Relatively small impact if interest rates are low.
• All-cash (debt-financed): New interest expense. Higher impact, especially in high-rate environments.
• All-stock: New shares issued, diluting existing shareholders. No cash cost, but per-share earnings are spread across more shares.
• Mixed: Combination of the above effects.

Tax Rate Assumptions

Make sure you use a consistent tax rate for all adjustments. The acquirer's marginal tax rate is typically used. Changes in tax rate assumptions can flip a deal from accretive to dilutive.

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Common Interview Questions

"Is it possible for a deal to be accretive but still a bad deal?"

Yes. A deal can be accretive to EPS but still destroy value. For example, if the acquirer overpays but the target has high near-term earnings, the deal might be accretive for a year or two but the acquirer may never earn a return on investment above its cost of capital. EPS accretion is a near-term metric; value creation is a long-term concept. This is a sophisticated answer that impresses interviewers.

"What makes a deal more accretive: paying with cash or stock?"

It depends on the acquirer's P/E and the cost of debt. If the acquirer has a high P/E (meaning its stock is "expensive"), paying with stock is often more accretive because fewer shares are issued for each dollar of acquisition price. If the acquirer has a low P/E but cheap debt is available, cash (debt-financed) might be more accretive.

"How do synergies affect accretion/dilution?"

Synergies increase pro forma net income without increasing the share count (in a stock deal) or the financing cost (in a cash deal). They always push the analysis toward accretion. The magnitude depends on the size and timing of the synergies.

"Walk me through a quick accretion/dilution analysis."

This is your chance to demonstrate the step-by-step process above. Start with the purchase price, determine how it is funded (cash, stock, or mix), calculate pro forma net income (combining both companies plus synergies minus financing costs), determine pro forma share count, and compare pro forma EPS to the acquirer's standalone EPS.

"A company with a P/E of 15x acquires a company at 12x P/E using all stock. Is it accretive or dilutive?"

Accretive (before considering additional adjustments). The acquirer's P/E is higher than the price it is paying in P/E terms. The acquirer is using "expensive" currency (high P/E stock) to buy "cheap" earnings. Each new share issued brings more earnings per share than it costs.

"What if the acquirer's P/E is 10x and the target's is 15x in an all-stock deal?"

Dilutive. The acquirer would be issuing "cheap" stock (low P/E) to buy "expensive" earnings. Each new share issued dilutes existing shareholders more than the target's earnings offset.

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Building the Full Merger Model

The accretion/dilution analysis is one output of a broader merger model. A complete merger model includes:

1. Sources and uses: How the deal is financed.
2. Purchase price allocation: How the premium over book value is allocated to goodwill and intangibles.
3. Pro forma income statement: Combining both companies, adding synergies, subtracting financing costs and new amortization.
4. Accretion/dilution output: The bottom-line EPS comparison.
5. Sensitivity analysis: How accretion/dilution changes under different assumptions (purchase price, synergies, financing mix, P/E ratios).

In an interview, you typically only need to walk through the accretion/dilution portion. But understanding how it fits into the full model demonstrates deeper knowledge.

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Sensitivity Analysis: What Drives the Result

Accretion/dilution is sensitive to several key inputs. A good analyst (and a good interview candidate) can articulate which levers matter most:

| Input | Impact on Accretion | |-------|-------------------| | Higher purchase premium | More dilutive (paying more for the same earnings) | | More synergies | More accretive (adding earnings at no incremental cost) | | More stock (vs cash) | Depends on relative P/E | | Higher interest rates | Cash deals become more dilutive (higher financing cost) | | Higher target growth | More accretive over time (growing earnings faster) | | More intangible amortization | More dilutive (non-cash charge against earnings) |

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Practice Until It Becomes Instinct

Accretion/dilution analysis is tested in virtually every IB superday. The concept is straightforward, but the nuances -- purchase accounting, synergies, financing mix, the P/E shortcut -- separate strong candidates from average ones. You need to be able to both walk through the full analysis step by step and quickly assess accretion/dilution using mental math.

IB Flash has extensive practice sets on accretion/dilution, merger models, EPS, and synergies -- from basic definitions to scenario-based questions that mirror real superday interviews. Build the instinct now so you can answer confidently under pressure.