Big 4 Strategy · EY-Parthenon
EY-Parthenon case interview prep: what they test and how to train
TL;DR
EY-Parthenon is the strategy arm of EY and is structurally the closest of the Big 4 strategy practices to MBB. The case interview leans heavily on commercial due diligence, market sizing, and growth strategy — partly because that is what the firm does, and partly because those skills filter for the candidates the firm wants. Expect quantitative depth, especially in commercial diligence cases.
Last updated: May 16, 2026. Written by the CaseXcel team.
What the EY-Parthenon case interview tests
EY-Parthenon cases test commercial judgment combined with quantitative rigor. Commercial due diligence cases are common: you are asked to assess whether a market is attractive or whether a target company is worth acquiring. That means market sizing, competitive landscape, customer dynamics, and a defensible point of view on the investment thesis.
Why strong candidates still fail
- Treating diligence cases like profitability cases. The question is "is the market or asset attractive," not "why are profits down."
- Weak market sizing. EYP cases lean on sizing more than MBB does.
- No investment recommendation. CDD cases close with a buy / no-buy / conditional view. Take one.
Prep tactics that move the needle
Drill market sizing daily
Top-down breakdowns, segment analysis, growth assumptions. The more fluent you are, the more time you have for the strategic layer.
Practice commercial due diligence cases specifically
They have a distinct structure (market attractiveness, competitive position, customer dynamics, financials). Practicing only profit cases leaves a gap.
Build a PE / strategy investor lens
Read a few public CDD reports. Recognize how a real diligence team frames a market.
Train the skills EY-Parthenon actually tests
Mental math, case math, market sizing, MECE structuring, and framework recall, drilled in a single 5-to-10-minute daily session. No accounts, no onboarding, no fluff. The same practice that gets EY-Parthenon candidates ready for the case.
FAQ
What is commercial due diligence and why does EY-Parthenon ask about it?
Commercial due diligence is an outside-in assessment of a market or a target company for an investor. EY-Parthenon does a lot of CDD work, so cases mirror real engagements: assess market attractiveness, competitive dynamics, and recommend whether to invest.
Is EY-Parthenon comparable to MBB?
On case interview rigor, yes. The firm is widely considered the closest of the Big 4 strategy practices to MBB. Compensation, exit options, and brand differ.