The merger model is one of the most important financial models you will encounter in investment banking — both on the job and in interviews. If you are preparing for superday interviews at bulge bracket or elite boutique banks, you need to understand how a merger model works, what drives accretion and dilution, and how to walk an interviewer through the key mechanics step by step.
In this guide, we will break down the merger model from the ground up. We will cover the core concept, walk through a step-by-step example, explain the key assumptions that matter most, and review the most common interview questions you should be ready for. If you want a comprehensive overview of technical interview topics, check out our free course for a structured introduction to everything you need to know.
What Is a Merger Model?
A merger model — sometimes called an accretion/dilution model or an M&A model — is a financial model that analyzes the impact of one company acquiring another. Specifically, it determines whether the transaction is accretive (increases the acquirer’s earnings per share) or dilutive (decreases the acquirer’s earnings per share) after the deal closes.
Investment bankers build merger models for virtually every M&A transaction they advise on. Whether you are working on a $500 million deal or a $50 billion mega-merger, the fundamental framework is the same. The merger model sits alongside the DCF analysis, enterprise value vs. equity value analysis, and comparable company analysis as a core valuation and advisory tool.
Why Accretion/Dilution Matters
Public company acquirers care deeply about EPS accretion and dilution because their shareholders and analysts are watching. If a deal is dilutive, it means the acquirer is paying a price that — at least in the near term — destroys value on a per-share basis. That does not necessarily mean the deal is bad (there may be long-term strategic value), but it creates a higher burden of proof for management to justify the acquisition.
Conversely, if a deal is accretive, the acquirer’s EPS goes up, which is generally viewed favorably by the market. Understanding this dynamic is critical because interviewers will test whether you can reason through why a deal might be accretive or dilutive — not just whether you can calculate the numbers.
Step-by-Step: How to Build a Merger Model
Here is the step-by-step process for building a basic merger model. In an interview, you may be asked to walk through these steps conceptually or work through a simplified numerical example.
Step 1: Project Standalone Earnings for Both Companies
Start by projecting the net income (or EPS) for both the acquirer and the target on a standalone basis. These are the earnings each company would generate if the deal did not happen. You will typically use consensus estimates or build a simple income statement projection. This connects to the broader skill of understanding how the three financial statements link together.
Step 2: Determine the Purchase Price and Deal Structure
Next, determine how much the acquirer is paying for the target and how the deal is being financed. There are three primary forms of consideration:
- All cash: The acquirer pays the full purchase price in cash, often funded by debt.
- All stock: The acquirer issues new shares to the target’s shareholders.
- Mixed (cash and stock): A combination of both, which is the most common structure.
The deal structure matters enormously because it determines the tradeoffs in the accretion/dilution analysis. Cash deals funded by debt create interest expense that reduces earnings. Stock deals create dilution from new shares issued. The relative cost of each form of consideration drives the final result.
Step 3: Calculate the New Share Count
If the acquirer is issuing stock as part of the deal, calculate how many new shares are being issued. This is typically the equity portion of the purchase price divided by the acquirer’s share price. Add these new shares to the acquirer’s existing share count to get the pro forma diluted share count.
Step 4: Estimate Financing Costs
For the cash portion of the deal, estimate the after-tax interest expense on any new debt raised. You also need to account for foregone interest income on any cash used from the acquirer’s balance sheet. Understanding the weighted average cost of capital (WACC) and cost of equity is helpful context here, even though the merger model focuses on the incremental cost of the specific financing used.
Step 5: Account for Synergies
Most mergers include projected synergies — cost savings (like eliminating redundant corporate functions) or revenue synergies (like cross-selling). These synergies increase the combined company’s earnings. In a merger model, you typically phase synergies in over 1-3 years and tax-affect them to reflect the after-tax benefit.
Step 6: Calculate Pro Forma EPS and Compare
Finally, combine everything:
- Start with the acquirer’s standalone net income
- Add the target’s standalone net income
- Subtract incremental interest expense (net of tax) from new debt
- Subtract foregone interest income (net of tax) on cash used
- Add after-tax synergies
- Subtract any incremental D&A from purchase accounting adjustments
- Divide by the new pro forma share count
Compare this pro forma EPS to the acquirer’s standalone EPS. If pro forma EPS is higher, the deal is accretive. If it is lower, the deal is dilutive.
Key Drivers of Accretion and Dilution
Understanding what drives accretion versus dilution is arguably more important than memorizing the mechanics. Here are the key factors:
P/E Arbitrage
The single biggest driver of accretion/dilution in a stock deal is the relative P/E ratios of the acquirer and target. If the acquirer has a higher P/E ratio than the target (meaning the acquirer’s shares are “more expensive”), the deal is more likely to be accretive. The acquirer is essentially using its highly valued currency to buy a cheaper stream of earnings.
Conversely, if the acquirer has a lower P/E than the target, the deal will likely be dilutive because the acquirer must issue a lot of shares (expensive currency) to acquire the target’s earnings.
Cost of Debt vs. Target’s Earnings Yield
In a cash deal, the key comparison is the after-tax cost of the debt used to fund the deal versus the target’s earnings yield (inverse of P/E). If the target’s earnings yield is higher than the after-tax cost of debt, the deal will likely be accretive. If the cost of financing exceeds the earnings being acquired, the deal will be dilutive.
Synergies
Synergies can turn a dilutive deal into an accretive one. The larger the projected synergies relative to the deal size, the more likely the deal becomes accretive — which is why management teams often highlight synergy estimates when announcing deals.
Purchase Price Premium
The higher the premium paid above the target’s current share price, the more dilutive the deal becomes (all else equal). A higher premium means the acquirer is paying more for the same stream of earnings.
Common Merger Model Interview Questions
Here are the most frequently asked merger model questions in investment banking interviews. Make sure you can answer each of these confidently. For a broader overview of technical preparation, our technical cheatsheet covers the full range of topics you should master.
“Walk me through a basic merger model.”
Use the six-step framework above. Start with standalone earnings, determine purchase price and structure, calculate new shares, estimate financing costs, layer in synergies, and compare pro forma EPS to standalone EPS.
“A company with a higher P/E acquires a company with a lower P/E in an all-stock deal. Is the deal accretive or dilutive?”
Accretive. The acquirer is using its highly valued stock to purchase a cheaper earnings stream, so fewer shares need to be issued relative to the earnings acquired.
“What is the difference between an all-cash deal and an all-stock deal in terms of accretion/dilution?”
In an all-cash deal, the key factors are the after-tax interest expense on debt raised and foregone interest income on cash spent. There is no share dilution. In an all-stock deal, there is no interest expense, but the acquirer’s share count increases. The form of consideration that is “cheaper” depends on the acquirer’s cost of debt versus its cost of equity — and the target’s earnings yield relative to those costs.
“What are synergies and how do they affect a merger model?”
Synergies are the incremental value created by combining two companies. Cost synergies (headcount reductions, facility consolidation) are more common and more credible. Revenue synergies (cross-selling, new market access) are harder to achieve and are often discounted. After-tax synergies flow directly to pro forma net income, pushing the deal toward accretion.
“What are purchase accounting adjustments and why do they matter?”
When an acquirer buys a target, the target’s assets are “written up” to fair market value on the combined balance sheet. This creates incremental depreciation and amortization expense that reduces pro forma earnings. Goodwill is also created (the premium paid above the fair value of net assets), which is tested for impairment annually but not amortized under GAAP.
A Simple Numerical Example
Let us walk through a quick example to make this concrete.
Acquirer: Share price = $50, Shares outstanding = 100 million, Net income = $500 million, EPS = $5.00, P/E = 10x
Target: Share price = $20, Shares outstanding = 50 million, Net income = $100 million, EPS = $2.00, P/E = 10x
Deal terms: 25% premium, all-stock deal. Purchase price = $20 x 1.25 = $25 per share x 50 million shares = $1.25 billion. New shares issued = $1.25 billion / $50 = 25 million shares.
Pro forma EPS: Combined net income = $500M + $100M = $600M. Pro forma shares = 100M + 25M = 125M. Pro forma EPS = $600M / 125M = $4.80.
Standalone EPS was $5.00, and pro forma EPS is $4.80 — so the deal is 4% dilutive. This makes sense: the acquirer paid a 25% premium, meaning the effective P/E paid for the target was 12.5x (vs. the acquirer’s 10x P/E), so the acquirer overpaid relative to its own valuation.
Now add $50 million of after-tax synergies: pro forma net income = $650M, pro forma EPS = $650M / 125M = $5.20 — and the deal becomes 4% accretive. This illustrates how synergies can flip a deal from dilutive to accretive.
How to Prepare for Merger Model Questions
The best way to prepare for merger model questions is to internalize the framework — not just memorize formulas. Interviewers want to see that you understand the intuition behind accretion and dilution. Practice explaining the P/E arbitrage concept, the cash vs. stock tradeoff, and the role of synergies in plain English.
If you are coming from a non-target school, strong technical preparation is especially important for standing out. Pair your merger model knowledge with a polished resume and a compelling cover letter to give yourself the best chance of landing interviews in the first place.
For the most thorough preparation, consider working with a coach who has been through the process themselves. At Wall Street Mastermind, we run students through hundreds of mock interview questions — including merger model walkthroughs — so they walk into their interviews with total confidence. You can also explore our free resources for additional study materials.
Want Personalized Interview Coaching?
If you are serious about breaking into investment banking, the best thing you can do is work with someone who has been through the recruiting process and knows exactly what top banks are looking for. At Wall Street Mastermind, we have helped over 2,500 students land offers at every bulge bracket and elite boutique bank on Wall Street. Book a free strategy call to learn how we can help you prepare for your interviews and maximize your chances of landing the offer.
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