Accretion/dilution analysis is one of the most important analytical tools in investment banking M&A. It’s also one of the most commonly tested concepts in IB interviews — and one of the areas where I see the most confusion among candidates who haven’t taken the time to really understand the mechanics.
In this post, I’m going to walk you through exactly what accretion/dilution analysis is, why it matters, how to build one, and how to interpret the results. By the end, you’ll have a clear mental model that you can use in interviews and on the job.
What Is Accretion/Dilution Analysis?
Accretion/dilution analysis (often called an “accretion/dilution model” or “A/D analysis”) is used in stock-for-stock or mixed-consideration M&A transactions to assess the impact of an acquisition on the acquirer’s earnings per share (EPS).
- If the acquisition increases the acquirer’s EPS, the deal is said to be accretive.
- If the acquisition decreases the acquirer’s EPS, the deal is said to be dilutive.
This matters to acquirer management, boards, and shareholders because EPS is a key driver of stock price. All else equal, a deal that boosts EPS is perceived favorably; a deal that reduces EPS can put pressure on the acquirer’s stock and management team.
A quick note: accretion/dilution analysis is most relevant for all-stock or mixed deals. In an all-cash deal funded by existing cash, EPS accretion/dilution depends mainly on the lost interest income on that cash — a simpler calculation. The interesting mechanics really come into play with share issuance.
The Core Logic: Why Does a Deal Become Accretive or Dilutive?
To understand accretion/dilution, you first need to understand the concept of a P/E ratio (price-to-earnings ratio) in this context.
Here’s the key insight:
- When an acquirer issues shares to buy a target, it’s effectively using those shares as currency.
- Each share the acquirer issues represents a claim on some amount of the acquirer’s earnings per share.
- In exchange, the acquirer gets the target’s earnings.
- If the acquirer’s P/E ratio is higher than the effective P/E it’s paying for the target, the deal is accretive.
- If the acquirer’s P/E ratio is lower than the effective P/E it’s paying for the target, the deal is dilutive.
In other words: if the acquirer is a “high P/E” company acquiring a “low P/E” target, the acquirer is picking up more earnings per dollar of stock issued than it’s giving away — so the deal is accretive. This is the logic behind many large-cap acquirers buying smaller companies at lower multiples.
This is a key conceptual point that interviewers love to ask about. If someone asks you “when would a deal be accretive?” you should be able to answer: when the acquirer’s P/E is higher than the effective deal P/E (purchase price divided by target earnings).
How to Build an Accretion/Dilution Model
Let’s walk through the mechanics step by step.
Step 1: Start with Standalone EPS for Both Companies
You need projected net income and fully diluted shares outstanding for both the acquirer and the target. Divide net income by shares outstanding to get standalone EPS for the acquirer.
For a simple model, you might use Year 1 projected net income (calendar year or fiscal year). For a more robust model, you’d project multiple years to assess accretion/dilution over time.
Step 2: Calculate the Purchase Price and Equity Issued
Determine the purchase price being paid for the target. In a stock deal, this is based on an offer price per share for the target’s fully diluted shares.
If the deal is all stock, calculate how many new acquirer shares need to be issued:
New Shares Issued = Equity Purchase Price / Acquirer Stock Price
These new shares dilute the acquirer’s share count and will need to be added to the denominator when calculating pro forma EPS.
Step 3: Calculate Transaction Adjustments
Several adjustments affect the pro forma earnings of the combined company:
Interest Expense on Acquisition Debt: If any portion of the deal is funded with debt, you’ll add new interest expense. This reduces pro forma net income. After-tax: multiply by (1 – tax rate).
Lost Interest Income on Cash Used: If the acquirer uses cash on hand to fund part of the deal, it loses the interest income it was earning on that cash. After-tax: multiply by (1 – tax rate).
Amortization of Intangible Assets: In an acquisition, purchase price is allocated to the target’s assets. Any premium above fair value of identifiable assets goes to goodwill (not amortized under US GAAP). But identified intangibles (customer relationships, technology, trade names) are amortized over their useful lives. This amortization is a new expense in the combined income statement, and it reduces pro forma net income. After-tax: multiply by (1 – tax rate).
Synergies: If the deal creates cost or revenue synergies, you can include them in the pro forma earnings. Cost synergies are more certain (and more commonly underwritten); revenue synergies are harder to achieve and often excluded from base case models. After-tax: multiply by (1 – tax rate). We cover synergies in more depth in our free resources.
Step 4: Calculate Pro Forma Net Income and EPS
Pro forma combined net income = Acquirer’s net income + Target’s net income +/- Transaction adjustments (interest, lost interest income, intangible amortization, synergies).
Pro forma shares outstanding = Acquirer’s existing shares + New shares issued to fund the deal (for stock consideration).
Pro Forma EPS = Pro Forma Net Income / Pro Forma Shares Outstanding
Step 5: Compare Pro Forma EPS to Standalone EPS
Compare the acquirer’s pro forma EPS to its standalone EPS:
- If Pro Forma EPS > Standalone EPS: the deal is accretive
- If Pro Forma EPS < Standalone EPS: the deal is dilutive
Express the difference as a percentage: (Pro Forma EPS – Standalone EPS) / Standalone EPS. A deal that increases EPS by 3% is “3% accretive.”
Common Interview Questions on Accretion/Dilution
Here are the questions I see most often in IB interviews:
“When is a deal accretive?”
A deal is accretive when the earnings yield of the target (1 / deal P/E multiple) exceeds the cost of the equity or financing used by the acquirer. In a pure stock deal, this means the acquirer’s P/E is higher than the deal P/E. In a cash deal, it means the after-tax cost of funding is lower than the target’s earnings yield.
“Can a dilutive deal still be a good deal?”
Absolutely — and this is an important nuance. Accretion/dilution is an EPS metric, and EPS can be a flawed measure of value creation. A deal that’s dilutive in Year 1 might be strongly accretive in Years 3 to 5 once synergies are realized. Strategic acquisitions (to enter a new market, acquire technology, or consolidate a fragmented industry) can create substantial long-term value even if they’re dilutive near-term.
Good interviewers want to see that you understand the limitation of accretion/dilution analysis as a stand-alone decision metric.
“What’s the difference between accretion/dilution and NPV analysis?”
Accretion/dilution focuses on EPS impact — it’s an accounting measure. NPV analysis focuses on whether the present value of expected cash flows from the acquisition exceeds the purchase price paid — it’s an economic measure. NPV analysis is theoretically superior but requires more assumptions and judgment.
Practical Considerations
A few things that come up in real deal work but often get glossed over in interview prep:
- Deal closing timing: Most models assume a deal closes mid-year or at year-end. A deal closing on July 1 only contributes half a year of the target’s earnings in Year 1. Make sure your model accounts for partial-year ownership.
- Tax rate normalization: Use the acquirer’s expected ongoing tax rate for the pro forma, not the target’s standalone rate.
- Goodwill: In the pro forma balance sheet, goodwill is created for any premium paid above the fair value of net assets. Under US GAAP, goodwill is not amortized but is tested for impairment annually.
- Sensitivity analysis: In practice, bankers always run sensitivity tables showing accretion/dilution at various synergy levels and purchase price assumptions. This gives a range rather than a single point estimate.
For a deeper dive into financial modeling concepts like this one, check out our technical cheatsheet, and take a look at our track record of students who’ve mastered these topics and landed top bank offers.
Bottom Line
Accretion/dilution analysis is a core M&A concept every IB candidate and analyst needs to know. The mechanics — starting with standalone EPS, calculating new shares issued, adjusting for interest, intangible amortization, and synergies, and arriving at pro forma EPS — are testable in interviews and used in live deals. More importantly, understanding why a deal is accretive or dilutive (the P/E ratio comparison logic) is what takes your answer from acceptable to excellent.
Practice building a simple A/D model in Excel until you can do it from scratch without a template. That level of fluency is what separates the analysts who struggle in their first months from those who hit the ground running. If you’re looking for personalized help mastering these concepts, check out how our coaching program works — see what our students have accomplished on our testimonials page.
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