Accretion Dilution Model (IB Interview Guide)

An accretion/dilution model estimates how a proposed acquisition changes the buyer’s earnings per share (EPS). To build one, combine both companies’ earnings, adjust for financing, new shares, purchase accounting, and any supported synergies, then compare pro forma EPS with the buyer’s standalone EPS. The result is useful, but it does not prove that a deal creates value.

Accretion/Dilution Overview and Interview Expectations

An accretion/dilution analysis compares the buyer’s EPS before a transaction with estimated EPS after it. In an investment banking interview, you may be asked to build a simple model, explain its key assumptions, or discuss how changes in financing and deal terms affect the result.

The formula is:

Accretion/(dilution) = (Pro forma EPS − Standalone buyer EPS) ÷ Standalone buyer EPS

A positive percentage means the model shows accretion; a negative percentage means dilution. There is no universal percentage that makes a deal good or signals a successful interview answer. The result depends on the assumptions, and your ability to explain them matters as much as the calculation.

I encourage candidates to start with a clear question: “What changes in the buyer’s EPS because of this transaction?” That keeps the model focused. It also helps separate the result from broader questions about strategy, deal value, and investment returns.

What an interviewer is testing

An interviewer usually wants to see whether you can connect accounting and transaction terms in a logical way. You should be ready to explain how consideration is funded, how financing affects earnings, whether new shares are issued, and which assumptions change the combined company’s net income.

A strong answer makes the model’s boundaries clear. State whether EPS is basic or diluted, name the forecast period, and identify which adjustments are included. If a fact is missing, say what assumption you would use and why. Do not present a made-up input as a known fact.

Model Components, Assumptions, and Calculation Requirements

A basic model starts with each company’s standalone earnings and adjusts for the deal. Pro forma net income includes the buyer’s and target’s earnings, less financing costs and other deal-related expenses, plus any supported benefits. Divide that figure by pro forma diluted shares to calculate pro forma EPS.

Build the model in a practical order

1. Calculate standalone EPS. Divide the buyer’s net income by its diluted shares. Record the target’s net income for the same forecast period.
2. Set the purchase consideration. Identify the cash, debt, and stock portions. Do not assume the buyer uses cash or issues shares unless the case says so or you state it as an assumption.
3. Calculate financing effects. Debt creates interest expense. Cash used in the deal may also reduce interest income the buyer would otherwise have earned.
4. Add other adjustments. These may include purchase-accounting expenses, deal costs, and synergies. Show each separately so the interviewer can see what drives the answer.
5. Calculate pro forma shares and EPS. Add newly issued shares to the buyer’s diluted shares, then divide adjusted net income by the result.
6. Compare with standalone EPS. Calculate the percentage change and explain the main drivers.

For stock consideration, use:

New shares issued = Stock consideration ÷ Buyer share price

For debt financing, a common simplified calculation is:

After-tax interest expense = Debt raised × Interest rate × (1 − Tax rate)

This assumes the interest expense receives the stated tax treatment. Apply a tax shield only if the model’s assumptions allow it. In a simple interview model, be explicit about the tax rate and avoid applying a tax effect twice.

Purchase accounting can affect earnings after the deal closes. For example, certain acquired assets may lead to additional depreciation or amortization. Synergies are expected savings or other benefits from combining the companies; include them only when the case provides support or you label them as an assumption.

Illustrative interview case

The figures below are invented for practice. They show the mechanics, not a recommended deal or industry benchmark.

Assume a buyer has net income of $100 million and 50 million diluted shares. Its standalone EPS is $2.00. It acquires a target with $20 million of net income for $100 million of consideration: $50 million in stock and $50 million in new debt.

Assume the buyer’s share price is $20, the debt interest rate is 6%, the tax rate is 25%, purchase-accounting expenses reduce after-tax earnings by $3 million, and expected synergies add $5 million after tax. Assume no foregone interest income or other adjustments.

The model suggests accretion under these assumptions. That result depends on the $5 million synergy estimate and other inputs. Without the assumed synergies, pro forma EPS would be about $2.19, or roughly 9% above standalone EPS. A change in one assumption can matter, so show the calculation rather than reporting only the final percentage.

Separate the key drivers

These effects can interact. For example, a higher buyer share price means fewer shares are needed for the same stock consideration, but the share price itself does not change the target’s earnings. Keep each input tied to the correct part of the calculation.

Practice Sequence, Common Errors, and Interview Performance

A useful practice routine moves from the core formula to a short sensitivity check. First build a clean base case. Then change a few assumptions and explain the effect. This is a low-friction way to prepare: a spreadsheet and a few practice prompts are enough to reveal whether you understand the drivers.

Stress-test the result

Sensitivity analysis means changing one or more inputs to see how the output responds. For the example above, raising the debt rate from 6% to 8% increases after-tax interest expense from $2.25 million to $3.00 million. Pro forma net income falls by $0.75 million, and EPS falls by about one cent, to roughly $2.27.

You can also test zero synergies, a different stock/debt mix, or a different purchase-accounting charge. Change one input at a time first. That makes the cause of each change easy to explain. If several assumptions move together, say so and describe the combined effect.

Avoid common modeling errors

• Mixing periods: Use buyer and target earnings from the same forecast period.
• Using the wrong share count: Confirm whether the task asks for basic or diluted EPS.
• Forgetting issued shares: Stock consideration increases the buyer’s share count.
• Omitting financing effects: Debt interest and foregone interest income can both matter, depending on the funding plan.
• Misusing the tax shield: Apply taxes consistently and only where the assumptions permit.
• Double-counting adjustments: Keep synergies, purchase-accounting charges, and financing costs in separate lines.
• Treating synergies as certain: Identify whether they are given, supported, or simply assumed.
• Calling accretion proof of value: EPS can rise even if the buyer overpays or assumes unrealistic benefits.

Explain the answer aloud

A clear interview response follows the model’s logic: “I start with each company’s earnings, adjust for financing and deal-related items, add any stated synergies, and divide by the combined diluted share count. Then I compare pro forma EPS with the buyer’s standalone EPS.”

After giving the result, name the largest drivers and one risk to the estimate. If the case lacks a tax rate or financing mix, ask for it or state your assumption. That shows care without getting stuck. The goal is not to force an accretive result; it is to produce a traceable one.

Investment-Banking Career Pathways and Deal-Team Application

This model is one technical topic used in investment banking recruiting and deal work. It does not require a single degree or a universal credential, but candidates benefit from accounting, corporate finance, and spreadsheet skills. In a banking role, the same logic supports transaction analysis and helps teams discuss how deal terms may affect reported earnings.

For students and career changers, use the topic as a skills check, not as a stand-alone career test. Practice the accounting links, learn to explain assumptions, and use internships or other relevant work to build evidence of analytical ability. Interview expectations vary by firm and role, so review the specific job description and recruiting guidance.

Accretion is only one lens on a transaction. A deal may increase EPS yet destroy value if the buyer pays too much, relies on unsupported synergies, or uses an unsuitable cost of capital. Conversely, dilution alone does not settle whether a transaction makes strategic sense. Treat the model as a way to examine earnings effects, not as a final verdict.

Frequently Asked Questions

These answers address common interview questions about building and interpreting a basic merger model. Keep responses direct, define any assumption you use, and distinguish the model’s EPS result from a broader judgment about deal value.

What does accretion mean?
Accretion means the buyer’s modeled pro forma EPS is higher than its standalone EPS for the period being analyzed.

What does dilution mean?
Dilution means modeled pro forma EPS is lower than the buyer’s standalone EPS for that period.

How do I calculate accretion or dilution?
Subtract standalone EPS from pro forma EPS, then divide the difference by standalone EPS. Multiply by 100 to express the result as a percentage.

How do I calculate shares issued in a stock deal?
Divide the value of stock consideration by the buyer’s share price. Add the resulting shares to the buyer’s diluted shares in the pro forma share count.

How does debt affect the model?
Debt usually adds interest expense. A simplified after-tax calculation is debt multiplied by the interest rate and by one minus the assumed tax rate, if that tax treatment applies.

Should I include synergies?
Include synergies when the case provides them or when you clearly state them as an assumption. Show them separately and test the result without them.

Can an accretive acquisition destroy value?
Yes. EPS accretion does not prove value creation. The buyer may overpay, assume unsupported benefits, or use an unsuitable cost of capital.

Is there a universal accretion threshold for interviews?
No. There is no universal percentage that proves a deal is good or guarantees a strong interview answer. Explain the assumptions, calculation, and main drivers.

What should I do if information is missing?
Ask for the missing input if appropriate. Otherwise, state a reasonable assumption, explain why you chose it, and make clear that the result depends on it.

What is the most important model check?
Reconcile the pro forma share count and net income adjustments. Confirm that financing costs, taxes, synergies, and purchase-accounting items are included once, in the correct place.

(This article was written by one of our staff writers, James Holloway. Visit our Meet the Team page.)