EY-Parthenon case interview: 4 practice cases with worked examples (2026)

The EY-Parthenon case interview is a live business problem, usually candidate-led: you clarify the question, build your own structure, ask for the data you need and drive to a recommendation. Cases lean towards the work the firm is best known for, commercial due diligence for investors and corporate buyers, so market sizing, growth drivers and 'is this worth the price?' come up again and again. Most processes run two rounds, each with case interviews and behavioural questions, and some offices add a numerical test or a written case. The details vary by country, office and level, so treat what follows as the common pattern and check your invitation.

EY-Parthenon is EY's strategy and transactions consulting arm. It grew out of the Parthenon Group, a Boston strategy firm EY bought in 2014, and competes with the strategy firms for due diligence, growth strategy and deal work. Our MBB vs Big 4 guide sets out how the groups differ.

Confirm two things with your recruiter: whether behavioural questions sit inside each case interview or in a separate conversation (candidates describe both), and whether any round includes a written case, which needs its own practice.

Our library has two cases written in EY-Parthenon's style, both candidate-led and framed for an investor. We add two deal cases written in other firms' styles: a private equity buyout in Bain's style and a corporate acquisition in McKinsey's interviewer-led style. Each has a guided walkthrough.

New to due diligence? Start with Ashgrove: sizing and growth, no valuation. Ridgeline is the hardest and closest to real diligence.

The core method is the same as at MBB: clarify, structure, analyse, recommend. The differences are in emphasis, and they come from the work: a firm that tells investors whether a market is real and a price is fair will test exactly that.

So practise sizing until it is automatic, and end every case with a number an investor can act on. Candidates trained only on interviewer-led cases often stall when nobody tells them what to analyse first; the case interview method lesson covers how to drive.

For each case: the prompt, a structure that fits, the first exhibit and its first calculations, then the hypothesis you would say out loud. The rest is left for you to play.

Ashgrove Growth: sizing small-business HR software (market sizing, software)

The prompt. Ashgrove Growth Partners is considering an investment in Fernhill HR, a cloud HR and payroll software company selling to small businesses across Europe. Before looking at Fernhill itself, Ashgrove wants an independent view: how big is the European market for HR and payroll software for small businesses, and how fast will it grow over the next five years?

A structure that fits. Define the market first. Ashgrove settles on the EU, UK, Norway and Switzerland; employer businesses with 1 to 49 staff; payroll and core HR software, excluding accountants' fees; 2025 revenue in euros. Build bottom-up by business size, since adoption and price differ sharply between a 3-person and a 40-person firm. Check it top-down, explain any gap, then grow each driver separately to 2030.

The first calculations. Start with headcount, because price is charged per employee. Micro firms: 9.5m × 3 = 28.5m employees. Small firms: 1.5m × 20 = 30m employees. So the 1.5m small firms employ more people than the 9.5m micro firms, despite being about 14% of the businesses. Now value the small-firm band: 30m × 55% = 16.5m paying employees × EUR 8 × 12 = EUR 1,584m a year. Higher adoption and a higher price on a larger headcount: this band will carry the market.

EY-ParthenonAshgrove Growth sizes small-business HR softwareMarket Sizing · Medium

Ashgrove Growth sizes small-business HR software

Finish the bottom-up, reconcile it with a top-down estimate, grow it to 2030 and test the target's plan.

Interviewer

Our client, Ashgrove Growth Partners, is considering an investment in Fernhill HR, a cloud HR and payroll software company that sells to small businesses across Europe. Before looking at Fernhill itself, Ashgrove wants an independent view of the market. How big is the European market for HR and payroll software for small businesses, and how fast will it grow over the next five years?

Start the caseGuided, step by step

Ridgeline Capital: a vet clinic roll-up at 16 times EBITDA (due diligence, healthcare services)

The prompt. Ridgeline Capital, a mid-market private equity fund, is bidding for Larkspur Veterinary Partners, a group of 145 vet clinics in the US Southeast. Larkspur's revenue has grown about 22% a year for three years, and the seller is asking $960m, 16 times last year's EBITDA. Ridgeline has four weeks until final bids and wants commercial due diligence.

A structure that fits. The market: size, fragmentation and growth split into pets × visits per pet × spend per visit, past against forward. The organic engine: growth at clinics Larkspur already owned, in visits and revenue per visit, and whether it has the vets. The acquisition engine: clinics left to buy, prices and integration. The plan and the price: rebuild the plan on your own assumptions and test the price against the fund's hurdle.

The market was worth about $11bn in 2025, and the 2019 to 2022 period includes the pandemic surge in pet adoption. The first calculations. Market value is the product of the three drivers, so its growth is roughly their sum: 1.0% - 0.5% + 5.5% = 6.0% a year from 2025 to 2028. The exact check, 1.010 × 0.995 × 1.055 = 1.060, agrees. That is well below the 9.7% of the pandemic years, and the seller's adviser is presenting a market growing close to 10%. Look at the mix too: from 2022 to 2025, visits grew only about 0.5% a year (1.5% more pets, 1% fewer visits each), so 7 of the 7.5 points of growth came from spend per visit.

EY-ParthenonRidgeline Capital bids for a vet clinic roll-upM&A · Hard

Ridgeline Capital bids for a vet clinic roll-up

Separate the market from the roll-up machine, read the clinic KPIs and find the price that clears the fund's hurdle.

Interviewer

Our client, Ridgeline Capital, is a mid-market private equity fund bidding for Larkspur Veterinary Partners, a group of 145 vet clinics in the US Southeast. Larkspur's revenue has grown about 22% a year for three years, and the seller is asking $960m, 16 times last year's EBITDA. Ridgeline has four weeks until final bids and has asked us for commercial due diligence. How would you approach it?

Start the caseGuided, step by step

Both are written in other firms' styles, but they ask the deal questions EY-Parthenon interviewers ask: one for a private equity fund, one for a corporate buyer.

Wrenfield Capital: a budget gym buyout (private equity, fitness; written in Bain's style)

The prompt. Wrenfield Capital, a mid-market private equity fund, has been offered Strata Gyms, a chain of 120 budget gyms, for $600m. The seller's plan shows EBITDA more than doubling in five years. Should Wrenfield buy, and if so, what should it pay?

A structure that fits. The market and the whitespace left for new sites. The standalone business: what one gym earns, membership and churn. The value creation plan, lever by lever, with its evidence. Then price and returns: year-5 EBITDA × exit multiple against the equity put in, and the most the fund can pay.

Site costs are almost all fixed and monthly churn is 5%. The first calculations. A member pays $25 × 12 = $300 a year, and costs are $900k, so breakeven is $900k ÷ $300 = 3,000 members. A mature site is 2,000 members clear of that. But the leverage cuts both ways: every 100 members is worth $30k, so a site with 10% fewer members (4,500) earns $1,350k - $900k = $450k, 25% less.

BainWrenfield Capital eyes a budget gym chainM&A · Medium

Wrenfield Capital eyes a budget gym chain

Read membership by opening cohort, rerun new-site payback and set a bid the fund can defend.

Interviewer

Our client, Wrenfield Capital, is a mid-market private equity fund. It has been offered Strata Gyms, a chain of 120 budget gyms, for $600m, and the seller's plan shows EBITDA more than doubling in five years. Wrenfield wants to know whether to buy Strata and, if so, what it should pay. How would you approach this?

Start the caseGuided, step by step

Atlas Logistics: a last-mile acquisition (corporate M&A, logistics; written in McKinsey's style)

The prompt. Atlas Logistics, a regional freight and warehousing operator, is considering buying Kestrel, a last-mile delivery company, for $340m. Atlas's CFO thinks the price is high. Should Atlas proceed? This case is interviewer-led, so it also trains you to answer exactly the question asked.

A structure that fits. Keep standalone value and synergies apart. What is Kestrel worth on its own, against comparable deals? What is it worth to Atlas: cost synergies, revenue synergies (haircut hard), integration costs? Does the price clear standalone value plus credible synergies? What could go wrong?

The first calculations. The CFO's worry first: $340m ÷ $18.9m = 18.0 times 2025 EBITDA. What does that buy? Revenue grew from $182m to $210m in two years: 210 ÷ 182 = 1.154, and the square root of that is about 1.074, so about 7.4% a year. EBITDA grew faster, about 11% a year, as the margin crept from 8.4% to 9.0%. Two flags sit in the same table: 85% of drivers are contractors, and three customers bring 38% of revenue.

McKinseyAtlas Logistics eyes a last-mile acquisitionM&A · Hard

Atlas Logistics eyes a last-mile acquisition

Find the synergy that carries the deal, haircut the soft ones and decide whether the price clears.

Interviewer

Our client, Atlas Logistics, is a regional freight and warehousing operator. They are considering acquiring Kestrel, a last-mile delivery company, for $340m. Their CFO thinks the price is high. Should they proceed?

Start the caseGuided, step by step

A commercial due diligence answers four questions for an investor, in order. Using that order in any EY-Parthenon case gives your structure a spine the interviewer will recognise.

Written cases and case tests. Some EY-Parthenon offices are reported to use a written case or case test: a pack of data or slides to work through in a fixed time, then a short presentation or discussion. Others add a numerical test early on. Formats differ by office, level and year, so ask the recruiter what each round contains.

• Lead with the answer. Put the recommendation and the one number behind it at the top of your first page or slide.
• One message per page. Write each page title as a full sentence that states the finding, not the topic.
• Time-box. Split the time roughly a third reading, a third analysing and a third writing, and stop analysing on time.

• You can define a market in five parts (geography, customer, product, channel, metric) in under a minute.
• You can build a segmented bottom-up and a top-down check, and explain the gap rather than average it away.
• You split growth into volume and price, and history into the forecast period, without being asked.
• In any roll-up or chain, your first question is how much growth was bought and how much was earned.
• You can go from EBITDA and a multiple to exit value, equity and a maximum price, out loud and without a calculator.
• You close with a number an investor can act on: a size, a growth rate or a price, then the facts behind it.
• You have six to eight behavioural stories with specific actions and results, and a real answer to 'why EY-Parthenon?'

Play each case twice. First live: talk out loud, drive the structure yourself and time it at 30 to 40 minutes. Then open the guided walkthrough and compare your answers step by step. Wherever you lost time or a number, spend the next day on the matching drill, not another case. Our market sizing questions guide is the best companion read.