Most Oliver Wyman practice pages spoil the firm's own sample answers before you have done the arithmetic. That is the wrong use of the only free material that actually reflects how the firm writes a case. The useful move is to treat the official careers-site samples as timed, calculator-free drills, then fill the sector gap with one original, OW-heavy mini-case you can work end to end.
After this page you will know which official samples to open first, what the interviewer is listening for while you work them, and how to run a financial-services investment case with a structure, an exhibit, clean math, and a recommendation that names the hurdle.
What the firm itself tells you to rehearse
Oliver Wyman's interview preparation page frames the case as collaborative problem-solving: treat the interviewer as a client who wants the problem solved. It then publishes a six-step method that is effectively a scoring rubric in public language: pinpoint the issue, break it down, pick an approach, analyze the issues, use numbers, and make a recommendation.
That order matters. Candidates who skip "pick an approach" and dive into the first number they see look busy and score poorly. Candidates who land a recommendation without a number look polished and still fail the sheet. The firm's own wording ends on "What should your client do?" Attach the deciding figure when you answer.
The same page links a set of free practice samples. Those samples are the primary source for this article. I will describe what each one trains and link the exact page. I will not reproduce their exhibits, intermediate math, or published sample answers. Work them on Oliver Wyman's site, not from a third-party summary.
The official sample set, used properly
As of September 2026, the careers interview-prep section links several medium and easy practice cases across retail, agriculture, energy, health, and leisure. The set is broader than the "Oliver Wyman only does banks" folklore that still circulates on forums.
| Official sample | Sector flavor | What it trains (without spoilers) | Link |
|---|---|---|---|
| Urban Grocers | Grocery logistics | Cost stack vs. volume upside; judgment when the margin is thin | Urban Grocers |
| Supermarket Pharmacy | Retail adjacency | Demand, payback hurdle, and second-order store effects | Supermarket Pharmacy |
| Dairy Farm | Agriculture / PE | Two-option comparison when percentages alone mislead | Dairy Farm |
| Oil Gas Price Strategy | Energy midstream | Segmented sizing then a viability test against a stated payback | Oil Gas Price Strategy |
| Autism Digital Device | Health / pricing | Cost, value, and competitor bounds before a price recommendation | Autism Digital Device |
| Poseidon Water Park | Leisure / sizing | Visitor and ancillary revenue build to a daily total | Poseidon Water Park |
Older chart-heavy cases such as Wumbleworld and Aqualine still appear in candidate folklore. Treat them as optional extras if you can find a durable primary link; the current careers set above is what the firm is actively pointing candidates to.
How to run each official sample. Blind first pass, 25 to 35 minutes, no calculator, no peeking at "reveal sample answer." Write your structure, force one clarifying question, pick which branch you will test first, then build the number. Only then open the firm's sample answer and score yourself against three questions: Did I restate the constraint? Did I choose a defensible first cut? Did my recommendation lead with a yes/no and the deciding figure?
If you fail the arithmetic, do not immediately re-read the case. Drill the math type for fifteen minutes, then retry from a blank sheet.
What actually differs from MBB practice
Oliver Wyman sits in Marsh McLennan's consulting family and is well known for deep financial services and insurance and asset management work. That reputation is real. The published practice samples, however, are deliberately generalist. Practice implication: industry vocabulary helps in later rounds and practice-area conversations; the case skill that is scored first is candidate-led structure plus stacked arithmetic against a hurdle.
Compared with a typical McKinsey interviewer-led case, you set more of the agenda yourself. Compared with many BCG or Bain drills that hand you the next question with the exhibit, you decide which analysis is worth the next three minutes. The interviewer will still coach if you ask a clean question. They will not rescue a wandering tree.
Written cases appear in some final rounds (exact format varies by office and year; treat "always" claims as folklore). Conversational interviews sit alongside cases on the firm's own prep page, so fit and motivation are not optional add-ons.
Where candidates leak points on OW-style cases
I stop listening when a candidate treats the constraint as decorative. If the client needs a two-year payback, every branch you open should either move the payback or explain why it cannot. Narrating a full profitability framework while ignoring the hurdle is how you burn eight minutes and still have no recommendation.
Second leak: unit chaos. Revenue per month mixed with investment in years. Loss-adjustment expense treated as if it were indemnity. The firm's tip to "be careful with simple calculations" is not filler; their samples reward candidates who keep units visible on the page.
Third leak: a recommendation that is a vignette. "I would explore piloting" is not a decision. Lead with the decision, then the number, then the one risk that could flip it.
Ned's rule. Before you touch the exhibit, write the client's hurdle in one line at the top of the page (payback years, margin floor, NPV sign, or absolute profit). Every calculation either closes that hurdle or is a digression you should skip.
Worked mini-case: Harbor Mutual claims triage (original)
This case is invented for practice. The numbers are internally consistent and fictional. It is built for an Oliver Wyman-heavy sector: property and casualty insurance, where the firm publishes substantial actuarial and insurance expertise.
Prompt
Harbor Mutual is a mid-sized U.S. P&C insurer. The COO wants to know whether to invest $18 million in an AI-assisted auto-claims triage platform. The board will approve only if the initiative pays back in four years or less on a simple undiscounted cash basis, and only if year-one run-rate benefit is at least $4.5 million. Triage would cover 60% of personal-motor claims and 40% of commercial-motor claims. On covered claims it would cut loss-adjustment expense (LAE) by 25% and cut indemnity "leakage" (overpayment versus peer benchmarks, currently 4% of claim cost) by half. Should Harbor Mutual proceed?
Structure I would propose out loud
- Economics against the hurdle — annual LAE savings plus leakage savings versus the $18M outlay and the $4.5M year-one floor.
- Coverage and adoption — whether 60%/40% coverage is realistic in year one, and what happens if coverage slips.
- Risk and ops — false declines, regulator and broker pushback, vendor lock-in, and claims-staff capacity.
- Recommendation — yes/no with payback years and the binding constraint.
I would test branch 1 first. If the economics fail the board thresholds, branches 2 and 3 are academic.
Exhibit (fictional last-year book)
| Line | Policies in force | Claims per year | Average claim cost | Average LAE per claim |
|---|---|---|---|---|
| Personal motor | 2,400,000 | 96,000 | $3,500 | $420 |
| Commercial motor | 180,000 | 18,000 | $8,000 | $900 |
Math
Covered claim volumes
- Personal: 96,000 × 0.60 = 57,600
- Commercial: 18,000 × 0.40 = 7,200
LAE savings (25% on covered claims)
- Personal: 57,600 × $420 × 0.25 = 57,600 × $105 = $6.05M
- Commercial: 7,200 × $900 × 0.25 = 7,200 × $225 = $1.62M
- LAE total ≈ $7.67M
Leakage savings (half of 4% of claim cost on covered claims)
- Effective cut = 2% of claim cost on covered claims
- Personal: 57,600 × $3,500 × 0.02 = 57,600 × $70 = $4.03M
- Commercial: 7,200 × $8,000 × 0.02 = 7,200 × $160 = $1.15M
- Leakage total ≈ $5.18M
Year-one run-rate benefit
- $7.67M + $5.18M = $12.85M, which clears the $4.5M floor with room.
Simple payback
- $18M ÷ $12.85M ≈ 1.4 years, inside the four-year board limit.
Sensitivity worth saying aloud: if coverage is only half of what management claims (30% personal / 20% commercial), benefits roughly halve to about $6.4M and payback stretches to roughly 2.8 years — still inside four years, but closer to the floor on year-one benefit. That is the risk conversation, not a reason to invent a new framework.
Recommendation
Yes, proceed with the $18M triage investment, contingent on a 90-day pilot that proves at least 50% of the modeled coverage rates. The base case clears both board hurdles: about $12.9M year-one benefit and roughly 1.4-year payback. The decision flips only if coverage stalls near one-third of the plan and leakage savings fail to materialize; those are the two metrics to put on the steering dashboard.
A practice sequence that matches the scoring sheet
Do not binge eight cases in one evening. Sequence beats volume.
| Day | Assignment | Pass criterion |
|---|---|---|
| 1 | Urban Grocers, blind | Structure stated before any cost line |
| 2 | Supermarket Pharmacy, blind | Constraint restated; recommendation leads with a number |
| 3 | Dairy Farm, blind | Absolute profit discussed when margins look similar |
| 4 | Oil Gas Price Strategy, blind | Sizing and viability kept as separate steps |
| 5 | Harbor Mutual (this page), timed 30 min | Hurdle written first; units never mix |
| 6 | One official case reworked from memory | Faster arithmetic, same recommendation quality |
| 7 | Live voice case or scored drill | External feedback on synthesis |
If day 2 or day 5 exposes slow multi-step math, pause the case library and run quick math and the math drill until you can hold three intermediate totals without rewriting the page.
CoachNed is not affiliated with Oliver Wyman or Marsh McLennan.
Practice this today
Open Urban Grocers on Oliver Wyman's site. Set a 30-minute timer. Do not reveal the sample answer until you have a one-minute recommendation. Then run Harbor Mutual from this page under the same rules.
When you want scored feedback without a partner, take the five-minute first rep at /start or an ~18-minute live voice case at /interview. For OW-style candidate-led structure and stacked arithmetic, use /drills/structure and /drills/math. Everything on CoachNed is open for seven days with no card; then $120 for a recruiting season or $49 a month.
Frequently asked questions
Where can I find official Oliver Wyman practice cases?
On the firm's entry-level interview preparation page, under the practice samples section. Each linked case includes prompts, evaluation criteria, and a revealable sample answer. Use the primary pages; do not rely on third-party recreations.
Are Oliver Wyman cases only about financial services?
No. The firm's industry strength in financial services and insurance is real, but the published practice samples span grocery, agriculture, energy, health devices, and leisure. Expect quantitative, candidate-led cases; do not expect every prompt to be a bank.
How quantitative is an Oliver Wyman case interview?
High enough that multi-step arithmetic without a calculator is the deciding skill on most of the official samples. The firm's own tips call out careful use of numbers and end on a client recommendation. Treat market sizing and payback math as core, not optional polish.
Should I memorize the official sample answers?
No. Memorizing published answers trains recognition, not problem-solving. Blind work, then compare. Interviewers rewrite numbers and constraints; the transferable skill is holding a hurdle while you build the tree.
How long should I spend on each official practice case?
Plan 25 to 35 minutes for a full blind pass, then 10 minutes comparing your path to the firm's sample answer. If you need more than that to finish the math, the bottleneck is arithmetic speed, not "more cases."
Sources
- Oliver Wyman interview preparation — six-step case method, conversational vs. case interviews, and links to practice samples. Checked 2026-09-24.
- Urban Grocers case interview — official easy retail/logistics practice sample. Checked 2026-09-24.
- Supermarket Pharmacy case interview — official payback-style practice sample. Checked 2026-09-24.
- Dairy Farm case interview — official two-option investment practice sample. Checked 2026-09-24.
- Oil Gas Price Strategy case interview — official energy growth and viability practice sample. Checked 2026-09-24.
- Autism Digital Device case interview — official pricing practice sample. Checked 2026-09-24.
- Poseidon Water Park case interview — official leisure sizing practice sample. Checked 2026-09-24.
- Oliver Wyman Financial Services — firm practice-area framing for FS work. Checked 2026-09-24.
- Insurance and Asset Management — insurance practice context for the Harbor Mutual mini-case sector. Checked 2026-09-24.
- Actuarial consulting — actuarial scale and insurance capability context. Checked 2026-09-24.