The case study in consulting and finance interviews

Types of cases

1. Market sizing:

• "How many tires sold in Switzerland each year?"
• Method: top-down or bottom-up, quantified hypotheses
• Criteria: logic, orders of magnitude, fluency

2. Profitability:

• "A cantonal bank loses 20% margin over 3 years. Why? How to react?"
• Method: decompose revenues and costs, identify the driver
• Criteria: structure (issue tree), prioritisation

3. Market entry:

• "Should Migros enter the premium organic supermarket market?"
• Method: market, competition, capabilities, finances
• Criteria: 360° analysis, justified recommendation

4. M&A / acquisition:

• "Should Roche acquire this biotech for USD 5B?"
• Method: valuation, synergies, risks, integration
• Criteria: financial sense, sensitivity to hypotheses

5. Operations:

• "A hotel chain has falling occupancy. Diagnosis?"
• Method: operations analysis + benchmarks + recommendations
• Criteria: pragmatism, execution focus

Ideal structure

A typical case lasts 30-45 min and follows:

1. Clarification (3-5 min): rephrase the question, identify the goal, list unknowns
2. Structure (3-5 min): present your framework (issue tree, MECE)
3. Analysis (15-20 min): dig each branch, calculate, make hypotheses
4. Synthesis (3-5 min): top-down recommendation + risks + next steps

Classic frameworks

Profitability:

Profit = Revenue - Cost
Revenue = Volume × Price
Cost = Variable costs + Fixed costs

Top-down market sizing:

Population → segments → adoption rate → frequency of use → unit revenue = TAM

Market entry:

1. Market: size, growth, segments
2. Competition: players, market shares, differentiation
3. Internal capabilities: strengths, weaknesses, experience
4. Financial: ROI, payback, NPV

4P / 7P (marketing):

Product, Price, Place, Promotion (+ People, Process, Physical evidence)

Mental math

Evaluators often ask for mental math:

• Percentages: 30% of 240 → 240×0.3 = 72
• Multiplications: 250 × 18 = 25 × 18 × 10 = 450 × 10 = 4,500
• Divisions: 1,200 / 17 ≈ 70 (1,200 / 20 = 60, adjust)
• Exponentials: 1.05^10 ≈ 1.63 (rule of 72)

Practice: 30 min/day on mentalmaths.com for 1 month.

Resources to train

Books:

• Case in Point (Marc Cosentino): consulting reference
• The McKinsey Way (Ethan Rasiel)
• Vault Guide to Consulting Interviews

Platforms:

• PrepLounge.com: 5,000+ cases, mock partners
• CaseCoach: premium prep
• Management Consulted: videos and frameworks
• RocketBlocks: structured cases

Mock interviews:

• 15-25 mocks minimum before a BCG/McKinsey interview
• Vary profiles (ex-consultants, prep peers, advanced candidates)
• Film yourself to analyse ticks and posture

Swiss specifics

• McKinsey Zurich: strict Anglo-Saxon process, fluent English accent
• BCG Zurich/Geneva: focus on local sectors (banking, pharma, industry)
• Bain Zurich: results culture, expect numeric depth
• Swiss banks (UBS, Pictet IB): focus on M&A, valuation, lean team
• Swiss boutiques (Lenz, Walder Wyss advisory): more legal-financial cases

D-day

• Water, paper, pen on the table
• Listen to the full question before starting (don't cut)
• Rephrase to confirm: signal of structure
• Request 30-60 sec of reflection: well-perceived
• Think aloud: transparency on your reasoning
• Conclude with a clear recommendation: no "it depends"