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EY-Parthenon Case Interview Examples: A Worked Practice Case

EY-Parthenon cases think like an investor: is this market attractive, is this company winning, and is the deal worth the price? Work through a full commercial due diligence case step by step, check your math as you go, and compare your answers to a model response.

By the Case Prep Team Updated October 1, 2026 16 min read

Candidate-ledYou are expected to drive

Deals and PEMost distinctive case theme

Written caseUsed in many offices

Group caseAdded in some offices

Start the practice case Read the EY-Parthenon interview guide

Format

What makes EY-Parthenon cases different

EY-Parthenon is EY's strategy arm, built on The Parthenon Group, which two former Bain consultants founded and EY acquired in 2014. A large share of its work supports private equity investors and corporate deals, and its cases follow that. Prep guides consistently place its case difficulty closer to MBB than to the rest of the Big Four.

The investor lens

Many cases end with a deal decision: should the fund buy this company, and at what price? You need to connect market facts and company performance to value, not just to strategy.

Market first

Commercial due diligence starts with the market: how big it is, how fast it grows, and which segments are winning. Expect weighted growth rates and market share math early in the case.

You drive the case

Live cases are generally candidate-led. Interviewers expect you to propose the structure, ask for the data you need, and keep moving toward an answer without prompting.

EY-Parthenon and EY Consulting recruit separately and interview differently. EY Consulting cases focus more on implementation, technology, and operations. If you are applying there, see the EY case interview examples instead.

Case types

Case types EY-Parthenon candidates report

These five themes cover most of what EY-Parthenon candidates describe. Each example prompt below is an original EY-Parthenon-style prompt, not a real interview question. Pick a tab to see how you would structure it and what math to expect.

Example prompt: A private equity fund is considering buying a chain of physical therapy clinics. Is it a good investment?
How to structure it: Cover the market (size, growth, reimbursement trends), the competition, the target's performance against peers, and the deal itself: price, value creation plan, risks, and exit.
Math to expect: Market growth by segment, market share, EBITDA margins, and a rough return on the purchase price.

Practice case

Worked practice case: ClearWave Car Wash

This is an original commercial due diligence case written in the style EY-Parthenon candidates describe. In a live interview you would drive the structure and ask for data yourself. Here, each step shows the question an interviewer would likely ask next so you can check yourself.

Answer each step out loud or on paper before you reveal the model answer. The suggested times match a strong candidate's pace.

Commercial due diligencePrivate equityAbout 25 minutes

ClearWave Car Wash: should the fund buy it?

Your client is a mid-sized private equity fund. It is considering buying ClearWave, a chain of 150 express car wash sites across the Southeast US. The seller is asking $600 million, which is 12 times ClearWave's $50 million in annual EBITDA. The fund would hold the business for five years. It has hired EY-Parthenon to assess whether the market and the company support that price. How would you approach this?

If you ask clarifying questions, the interviewer shares:

Express sites offer quick, exterior-only washes, and most of their revenue comes from monthly unlimited-wash memberships.
The fund plans to finance 60% of the price with debt.
The fund's management plan would add 15 new sites a year.

0 of 6 steps revealed

Structure the diligence

Take about 2 minutes

Interviewer: How would you structure your diligence?
The core question: can ClearWave grow EBITDA enough over five years to earn the fund a strong return at a $600M price? I would look at four areas:
- Market: size and growth by segment, and what drives demand, like membership adoption and new site openings.
- Competition: how fragmented the market is, who is consolidating it, and how many new sites are being built nearby.
- The company: revenue and margin per site, membership retention, and how quickly new sites ramp up.
- The deal: the value creation plan, likely exit value, and the risks that could hurt returns.
Why it works: it opens with the investor's real question, then moves from market to company to deal, the same order a diligence report follows.
Read the market exhibit

Take about 3 minutes

Interviewer: Here is the US car wash market by segment. What is the overall market growth rate, and what does the data tell you?

Exhibit 1: US car wash market by segment

Segment Revenue ($B) Annual growth

Express exterior 6.0 9%

Full-service 4.0 1%

In-bay automatic 3.0 -2%

Self-serve 1.0 -4%

Total 14.0 ?

Illustrative data for practice.

Overall market growth (%)
Size ClearWave's position

Take about 3 minutes

Interviewer: An average ClearWave site has 2,000 members paying $30 a month and earns another $480K a year from single washes. What share of the express exterior segment does ClearWave hold?

Share of express segment (%)
Estimate the return

Take about 4 minutes

Interviewer: The fund's plan grows EBITDA from $50M to $80M in five years. If it sells at the same 12 times multiple, what multiple of the $600M purchase price is the exit value?

Exit value as a multiple of price (x)
Test the key risks

Take about 2 minutes

Interviewer: What would you want to confirm before the fund commits?
- Market: how many competing express sites are being built near ClearWave's locations, and whether growth slows as the segment matures.
- Memberships: how many members cancel each month, how that varies by site age, and whether past price increases drove members away.
- New sites: how long new sites take to reach mature revenue, and whether new sites pull customers away from existing ones.
- Deal: whether 12 times is a fair price compared with recent car wash deals, and how much the return depends on selling at the same multiple.
Each question maps to a specific number in the fund's plan. That is what makes it diligence rather than a generic list of risks.
Make the recommendation

Take about 1 minute

Interviewer: The fund's partner just joined the call. What is your view?

Segment	Revenue ($B)	Annual growth
Express exterior	6.0	9%
Full-service	4.0	1%
In-bay automatic	3.0	-2%
Self-serve	1.0	-4%
Total	14.0	?

Math

Deal math quick check

EY-Parthenon cases lean on a small set of deal calculations: growth, margins, valuation, and returns. Try these four without a calculator, and aim for under a minute each.

A $10B market grows 7% a year. Roughly how big is it in 10 years?

Market size ($B)

A company has $240M in revenue and $36M in EBITDA. What is its EBITDA margin?

EBITDA margin (%)

A company earns $25M in EBITDA and sells for 10 times EBITDA. It has $100M of net debt. What is its equity worth?

Equity value ($M)

A fund invests $400M and sells its stake five years later for $720M. What multiple of its money does it make?

Multiple of money (x)

Other formats

Written and group cases

Beyond live cases, EY-Parthenon uses two formats that many candidates have not practiced. Ask your recruiter which you will get, since they vary by office.

The written case

You work alone with a data packet, often 15 to 25 pages, and have roughly 60 to 90 minutes to analyze it and build a short presentation of three to five slides. Then you present to interviewers and take questions. Decide on your recommendation early, give each slide a clear takeaway as its title, and flag any assumptions you could not confirm from the packet.

The group case

Some offices put you in a group of around five candidates with a shared case. You get about 45 to 60 minutes to review the materials and prepare a 15-minute group presentation, while interviewers watch but do not step in. Questions follow. You are assessed on how you work with others as much as on the answer, so build on other people's ideas, keep the group on time, and make sure your contribution is visible without dominating.

The exhibit drills are good practice for pulling insights out of a data packet quickly.

Prep plan

A two-week prep plan for an EY-Parthenon case

Days 1 to 3
Learn the basics of private equity: how funds make money, what EBITDA multiples mean, and how debt affects returns. Then practice structuring due diligence and market entry cases with the frameworks guide.
Days 4 to 6
Drill math daily: weighted growth rates, market share, margins, and return multiples.
Days 7 to 8
Practice market sizing until you can build and sanity-check an estimate in under three minutes.
Days 9 to 11
Run full candidate-led cases with a partner, including at least two due diligence cases. Redo ClearWave from memory and time yourself.
Days 12 to 14
Do one timed written case, prepare your fit stories, and have a specific answer to why you want EY-Parthenon rather than EY Consulting or another strategy firm.

Keep preparing

EY-Parthenon interview guideRounds, formats, and what interviewers look for. EY-Parthenon salariesPay by level, compared with core EY Consulting. EY-Parthenon application deadlinesDates and timeline for the next cycle. EY case examplesA worked case for EY Consulting.

FAQ

Frequently asked questions

What kind of cases does EY-Parthenon give?

Expect commercial due diligence for private equity investors, along with market entry, growth strategy, and market sizing cases. Many cases end with a judgment on whether a deal is worth the price.

Are EY-Parthenon cases candidate-led?

Generally, yes. Interviewers expect you to set the structure, ask for data, and drive toward a recommendation. Some first-round cases are more structured, so be ready for either style.

Do I need to know private equity for EY-Parthenon interviews?

You do not need finance training, but you should understand the basics: EBITDA, valuation multiples, how debt affects a fund's return, and what makes a business attractive to investors.

Does EY-Parthenon have a written case or group case?

Many offices use a written case, where you analyze a data packet and present a few slides. Some also run a group case with other candidates. Confirm the format with your recruiter.

How is EY-Parthenon different from EY Consulting?

EY-Parthenon is EY's strategy arm. It recruits separately and runs harder, more strategy and deal focused cases, closer to MBB. EY Consulting cases focus more on technology, operations, and implementation.

Is the ClearWave case a real EY-Parthenon case?

No. It is an original practice case written to match the style EY-Parthenon candidates describe. All numbers are illustrative.

Sources

Hacking the Case Interview, EY-Parthenon Case Interview: How to Prepare. hackingthecaseinterview.com. Accessed October 2026.
IGotAnOffer, EY-Parthenon Case Interview Guide. igotanoffer.com. Accessed October 2026.
Management Consulted, EY-Parthenon Case Interview. managementconsulted.com. Accessed October 2026.
MyConsultingOffer, EY Case Interview Including EY Parthenon. myconsultingoffer.org. Accessed October 2026.

Case Prep is an independent practice platform and is not affiliated with, authorized by, or endorsed by EY or EY-Parthenon. The ClearWave case, example prompts, and all data on this page are original teaching material.