Cornerstone Research Case Interview Guide: Process, Economic Analysis Cases, and Worked Examples

69% of Cornerstone Research candidates on Glassdoor rate the interview experience positively, with a 3.3/5 difficulty score (Source: Glassdoor 2026). The process runs two rounds over 17 days on average: virtual interviews with behavioral-case splits, then an in-person Super Day with four 45-minute case interviews. These cases differ fundamentally from MBB. Instead of "should this company enter a new market," you will analyze "what is the economic damage from this alleged antitrust violation?" -- backing your answer with data analysis and regression intuition.

Cornerstone Research vs. Management Consulting: What Changes

If you are coming from MBB case prep, you need to recalibrate. The toolkit overlaps, but context and evaluation criteria diverge sharply.

The most common mistake we see: candidates try to "structure" a Cornerstone case with a profitability tree or market entry framework. When Cornerstone asks "how would you assess damages from alleged price-fixing," the answer involves defining the but-for world, identifying a control group, and isolating the overcharge using regression -- not revenue and cost buckets.

The 4 Cornerstone Case Types

Based on 200+ reported interview experiences on Glassdoor and Wall Street Oasis, Cornerstone cases cluster into four categories.

1. Antitrust and Market Definition

Example: "A tech company controls 75% of search advertising. The DOJ alleges monopoly. Define the relevant market and assess whether 75% share proves market power."

Approach: Apply the SSNIP test (would a 5-10% price increase be profitable?), distinguish narrow vs. broad market definitions (search ads vs. all digital ads), assess barriers to entry, and reference the HHI (above 2,500 = highly concentrated). Market share alone never proves monopoly power.

2. Securities Litigation and Event Studies

Example: "A pharma company's stock dropped 22% after disclosing a failed trial. Plaintiffs claim the company withheld data for 6 months. Estimate damages."

Approach: Build a market model regression (stock returns as a function of S&P 500 + industry index), calculate the abnormal return on the disclosure date, and multiply by shares outstanding. This is the methodology in Cornerstone's published "Zilo" case example (Source: Cornerstone Research Analyst Case Examples).

3. Damages Calculation

Example: "A retailer claims a supplier breach caused $15M in lost sales. Assess this figure."

Approach: Construct the but-for scenario (what would have happened absent the misconduct) using comparable benchmarks or the firm's pre-breach trend. Use regression to control for seasonality, macro conditions, and competitive entry. Damages = but-for sales minus actual sales.

4. Valuation Disputes

Determine fair market value when two parties disagree. Uses DCF, comparables, and precedent transactions -- similar to data interpretation skills but in a legal context where the valuation may determine billions in damages.

The Regression Intuition You Need

Cornerstone's career page states candidates should "have an intuitive grasp of what a regression is." You will not code one. You will reason about one.

Framework

Regression Analysis Framework for Cornerstone Cases

1. 01

   Step 1: Define the Dependent Variable

   What outcome are you measuring? Stock returns, sales, market prices.

2. 02

   Step 2: Identify Independent Variables

   What explains variation in Y? Market returns, industry trends, seasonal factors.

3. 03

   Step 3: Choose Controls

   Economy-wide shocks, industry trends, unrelated firm events. Omitting a relevant variable biases results.

4. 04

   Step 4: Assess Significance

   Is the coefficient statistically different from zero? p-value < 0.05 and confidence intervals.

5. 05

   Step 5: Test Robustness

   Does the result hold with different time windows, controls, or specifications?

Key concepts: (1) Omitted variable bias -- in the Zilo case, omitting industry returns wrongly attributes market declines to the firm. (2) Statistical vs. economic significance -- p < 0.05 on a $0.02 effect is detectable but meaningless on a $500 product. (3) Endogeneity -- circular causation between variables.

Worked Example: Event Study Damages

Prompt: TechCo disclosed on March 15 that it overstated revenue by $200M. Stock fell from $85 to $62. TechCo has 150M shares outstanding. Plaintiffs claim $3.45B damages ($23 × 150M shares). You are retained by the defense.

Build the market model: Regress TechCo daily returns on the S&P 500 and a software index using 250 pre-event trading days. Result: TechCo Return = 0.2% + 1.3 × (S&P) + 0.8 × (Software Index).

Predict expected return on March 15: S&P fell 1.2%, software index fell 2.5%. Predicted return = 0.2% - 1.56% - 2.0% = -3.36%.

Calculate abnormal return: Actual return = ($62 - $85) / $85 = -27.06%. Abnormal return = -27.06% - (-3.36%) = -23.7%. Market and industry factors explain 3.36 points of the decline.

Compute damages: Damages/share = $85 × 23.7% = $20.15 (not $23). Total = $20.15 × 150M = $3.02B (not the plaintiff's $3.45B). By controlling for systematic factors, you reduce damages by $430M.

Key insight: The naive "total decline × shares" calculation ignores market movements. Every Cornerstone event study case tests whether you separate firm-specific impact from market noise.

Cornerstone vs. Other Economic Consulting Firms

For deeper comparisons, see our NERA case interview guide and Analysis Group guide. Cornerstone places the heaviest emphasis on securities litigation and event studies among this group.

The Interview Process: Round by Round

Round 1 (Virtual): Two back-to-back 30-minute interviews. Each splits 50/50 between behavioral questions and a mini case. Expect: "Why economic consulting over management consulting?" and "Walk me through a research project where you defended your methodology." The mini case presents a 1-page scenario with data and 3-4 directed questions.

Round 2 (In-Person Super Day): Four consecutive 45-minute interviews with staff at different levels. Cases provide multi-page exhibits (regression outputs, stock charts, market share data). You are expected to critique the analysis, not just follow instructions. Interviewers probe: "What if I added this control variable?" and "How would your conclusion change with a shorter estimation window?" The dinner afterward is informal but evaluative.

How to Prepare

1. Economics foundations: Review supply/demand, market structure, price discrimination, and basic econometrics (OLS, hypothesis testing, omitted variable bias). Read Cornerstone's published analyst case examples at cornerstone.com/careers/analyst/analyst-case-examples.
2. Practice case types: Work through 2-3 antitrust and 2-3 event study scenarios. Practice interpreting regression output tables and sharpen case math skills.
3. Mock interviews: Do 4-6 mocks in interviewer-led format. Practice the behavioral half. Review case interview frameworks for the rare strategy-adjacent case.

Quiz: Test Your Economic Consulting Knowledge

Test yourself

1 / 3

Question 1 of 3

In an event study, TechCo's stock drops 15% on the disclosure date. The market model predicts a -3% return based on S&P and industry movements. What is the abnormal return?

• A-15% (the full decline is abnormal)
• B-12% (actual return minus predicted return)
• C-18% (add the predicted decline to the actual)
• D-3% (only the market component matters)

Common Mistakes

Salary and Exit Opportunities

Analyst base averages ~$108K (range $83K-$142K at 25th-75th percentile); Associates earn ~$255K median total compensation (Source: Glassdoor 2026). Cornerstone operates a staffing model -- you rotate across practice areas and work directly with academic experts (often tenured economics professors).

Top exits: PhD programs in economics (Cornerstone's strongest placement track), law school, MBA programs, lateral moves to NERA or Analysis Group, data science, and investment banking.

Sources

1. Glassdoor: Cornerstone Research Interview Experience (69% positive, 3.3/5 difficulty) — glassdoor.com/Interview/Cornerstone-Research-Interview-Questions-E23016.htm (checked April 8, 2026)
2. Wall Street Oasis: Cornerstone Research Interview Questions (67 entries) — wallstreetoasis.com/company/cornerstone-research/interview (checked April 8, 2026)
3. Cornerstone Research: Analyst Case Examples (Zilo event study) — cornerstone.com/careers/analyst/analyst-case-examples (checked April 8, 2026)
4. Cornerstone Research: Office Locations — cornerstone.com/about/offices (checked April 8, 2026)
5. Management Consulted: Cornerstone Research Overview — managementconsulted.com/cornerstone-research (checked April 8, 2026)
6. Glassdoor: Cornerstone Research Salaries ($108K analyst average) — glassdoor.com/Salary/Cornerstone-Research-Salaries-E23016.htm (checked April 8, 2026)
7. Hacking the Case Interview: Cornerstone Research Case Guide — hackingthecaseinterview.com/pages/cornerstone-research-case-interview (checked April 8, 2026)
8. CaseInterview.com: Cornerstone Research 2026 Profile — caseinterview.com/cornerstone-research (checked April 8, 2026)