Compass Lexecon Case Interview Guide 2026: Process, Cases & Prep

Compass Lexecon is best known for antitrust and competition economics, and its interviews look nothing like a standard management consulting case. Instead of a profitability tree, you analyze a merger, competition, or damages scenario using applied microeconomics and econometrics, then defend your conclusions to economists. This guide covers the real format candidates report, two fully worked cases, current salary benchmarks, and a focused 4-week plan. Treat process and pay numbers from third-party sites as directional, and confirm the exact format for your office and role with your recruiter.

What does the Compass Lexecon interview process look like?

The sequence varies by office, role, and practice. Candidate reports can suggest possible components, but your invitation is the source of truth.

Stage 1: Screening and reasoning test

Some candidates report a phone or video screen and a numerical or verbal reasoning test. Confirm the interviewer, content, and timing from your invitation.

Common screening questions:

• Why economic consulting over management consulting or academia?
• Why Compass Lexecon specifically, versus NERA, Analysis Group, or CRA?
• Walk me through a time you used data to solve a problem.
• Which econometric methods and tools (Stata, R, EViews) are you most comfortable with?

Stage 2: The written economics case

If your process includes a written case, use the packet length, data format, output, analysis time, and presentation time stated in your invitation.

What the case looks like: Candidate reports describe two recurring archetypes. The first is a merger review, for example analyzing a vertical merger between a car manufacturer and a battery producer from a competition authority's perspective: define the relevant market, assess competitive effects, evaluate efficiency claims, and recommend remedies, all supported by the data provided. The second is a damages or price-fixing case where you estimate an overcharge against a but-for benchmark. We work both below.

Even though the lens is antitrust rather than deal advisory, the underlying reps overlap with a management-consulting acquisition case: valuation, synergy realism, and what conditions create or destroy value. Running one end to end sharpens the same logic.

Stage 3: Presentation and follow-up

If your process includes a presentation, prepare to defend your market definition, test alternative explanations, and refine the analysis in response to questions. Follow the invitation's timing.

How is a Compass Lexecon case different from a McKinsey case?

Understanding this distinction is the single most important thing to get right in prep.

That said, the underlying problem-solving loop is shared. Economic cases still reward a clarified objective, a structured (MECE) breakdown, transparent calculation, a qualitative read, and a clear recommendation. If you have been preparing with standard frameworks, keep the structure habit and supplement it with the economics-specific content below.

How should you align your Compass Lexecon resume and cover letter before this interview?

Write for the selected practice and make assumptions explicit. The resume should prove quantitative or research ownership, while the letter explains why that evidence fits the role and office.

• Before: Built an economic model.
• After: Compared two demand assumptions, tested the sensitivity, and summarized the implication for the project recommendation.

Check that you can explain the assumptions and use a safe proxy for confidential details. Recruiters read the documents together: the resume proves the analytical work, while the cover letter explains fit and motivation. Rehearse the revised line as a concise assumptions discussion before the guide's worked cases.

Revise one model line, rehearse the decision rule, and use it in the next economic-case rep.

Worked example 1: Merger review and HHI

Here is a simplified version of the merger archetype.

Scenario: FreshCo (a grocery chain with 30% market share) proposes to acquire GreenMart (15% share) in a metro area with 5 other competitors (7 players total). The competition authority asks you to evaluate.

Step 1: Define the market. The relevant market is grocery retail within roughly a 20-mile radius of the metro area. Apply the SSNIP test (Small but Significant Non-transitory Increase in Price): if a hypothetical monopolist could profitably raise prices 5-10%, the market is correctly drawn. If customers would simply switch to outside options, your market is too narrow.

Step 2: Measure concentration. The Herfindahl-Hirschman Index (HHI) is the sum of squared market shares.

Pre-merger HHI = 30² + 15² + 12² + 11² + 10² + 8² + 14² = 900 + 225 + 144 + 121 + 100 + 64 + 196 = 1,750.

Post-merger, FreshCo and GreenMart combine to 45%, so:

Post-merger HHI = 45² + 12² + 11² + 10² + 8² + 14² = 2,025 + 144 + 121 + 100 + 64 + 196 = 2,650.

Delta HHI = 2,650 - 1,750 = 900. There is a shortcut worth knowing: the change in HHI from a merger equals twice the product of the two merging shares, so 2 × 30 × 15 = 900. Both methods agree, which is a fast self-check under time pressure.

Step 3: Apply the screen. Under the 2023 Merger Guidelines, a market with HHI above 1,800 is highly concentrated; a merger increasing HHI by more than 100 points in such a market triggers the structural presumption.

Step 4: Read the competitive-effects evidence. Now interpret the regression output provided, for example a diversion ratio showing that 40% of FreshCo customers who leave switch to GreenMart. A high diversion ratio means the two are close substitutes, which implies meaningful upward pricing pressure post-merger. This is closer to data interpretation than standard case math.

The skill being tested here, reading an exhibit and pulling the decision-relevant number out of it fast, is exactly what graph and data-interpretation drills build.

Step 5: Weigh the efficiency defense. FreshCo claims $50M in annual supply-chain savings. You assess whether they are merger-specific (not achievable any other way), verifiable, and likely to be passed through to consumers. Unverifiable or non-specific efficiencies carry little weight. Your recommendation might be: block, or clear subject to a structural remedy such as divesting overlapping stores.

Worked example 2: Damages and the overcharge

The second archetype is a damages case, common in price-fixing and litigation work. Here the question is not "should this merger proceed" but "how much did the conduct cost buyers."

Scenario: Phone manufacturers suspect battery suppliers of fixing prices in 2009-2010. You are asked to estimate the overcharge per unit.

Step 1: Build the but-for benchmark. Establish what the price would have been absent collusion. Suppose batteries trended down by $0.50 every other year, implying a but-for price of about $18.00 in 2009 and $17.50 in 2010.

Step 2: Measure the actual gap. Suppose actual prices were $21.50 and $21.00. The raw overcharge is $21.50 − $18.00 = $3.50 in 2009 and $21.00 − $17.50 = $3.50 in 2010, so $3.50 per unit.

Step 3: Control for alternative explanations. A natural disaster raised production costs in those years, so not all of the $3.50 is collusion. By comparing profit margins per battery across years, you isolate an unexplained margin increase of about $1.50 per unit beyond what cost shocks justify. That $1.50 is the defensible overcharge attributable to the conduct; the remaining $2.00 is legitimate cost pass-through.

Step 4: Scale and sanity-check. If 200 million units sold over the period, the estimated damage is 200M × $1.50 = $300M. Then pressure-test it: is demand elastic enough that buyers absorbed some of the increase, and does the benchmark period itself look clean? Naming these limitations is what separates a strong answer from a number with no error bars.

This structured economic analysis, not a profitability case framework, is what Compass Lexecon assesses.

What does Compass Lexecon pay in 2026?

Treat third-party compensation data as market references, not official pay bands. Actual offers vary by office, level, degree, start date, and market conditions.

Sources to triangulate: Glassdoor salary data, Wall Street Oasis, recruiter materials, and location-specific offer discussions. Self-reported figures can lag current offer bands.

The useful prep takeaway is practical: know your target office, degree level, and role category before you benchmark, because a single national average hides large location and degree gaps.

How does Compass Lexecon compare to other econ consulting firms?

For detailed competitor guides, see our NERA case interview guide, Analysis Group guide, and Charles River Associates guide.

Which technical concepts must you know?

These appear most often in Compass Lexecon-style interviews:

Microeconomics:

• Market definition using the SSNIP test (hypothetical monopolist test)
• HHI calculation and interpretation (pre-merger, post-merger, delta)
• Deadweight loss from market power
• Price discrimination (first, second, third degree)
• Vertical restraints and foreclosure theory

Econometrics:

• Interpreting OLS regression output (coefficients, standard errors, R², p-values)
• Difference-in-differences estimation
• Instrumental variables and endogeneity
• Selection bias and omitted variable bias

Antitrust and damages frameworks:

• Horizontal and vertical merger analysis (unilateral effects, foreclosure, raising rivals' costs)
• Relevant market definition (product market, geographic market)
• Diversion ratios and upward pricing pressure (UPP)
• But-for benchmarks and overcharge estimation in damages cases
• Merger remedies (structural vs behavioral)

What is a focused 4-week prep plan?

Execution checklist

• ✓

  Week 1: Review IO microeconomics (market structure, pricing, welfare analysis). Compass Lexecon cases are rooted in industrial organization theory. Price theory, market power analysis, and welfare economics need to be automatic before you tackle a timed case.

• ✓

  Week 1: Refresh econometrics (OLS interpretation, D-in-D, IV estimation). The written case includes regression output. If you cannot read coefficients, p-values, and spot endogeneity within 2 minutes, you will run out of time on a 60-90 minute clock. Pressure-test the skill with a timed case.

• ✓

  Week 2: Study 3 real competition matters (FTC v. Meta, Illumina/Grail, Microsoft/Activision). Interviewers expect you to reference real cases, and these are matters Compass Lexecon itself advised on. Knowing the economic arguments on both sides shows genuine interest in the field.

• ✓

  Week 2: Practice 1 timed written case end to end (read packet, write recommendation in 75 minutes). Reading a 10-15 page packet and writing a concise recommendation under time is a distinct skill from knowing the economics. Practice the actual format, not just the theory.

• ✓

  Week 3: Run 4 verbal presentation drills defending your written analysis. Economists challenge your conclusions in the 40-minute follow-up. Practice defending market definition and overcharge estimates under questioning, not just presenting them.

• ✓

  Week 3: Prepare answers for 'Why economic consulting?' and 'Why Compass Lexecon?'. Screening filters heavily on motivation. 'I like data' is not enough. Tie your answer to a specific practice area, real Compass Lexecon work, and your quantitative background.

• ✓

  Week 4: Review Stata/R basics (loading data, running a regression, reading output). Some offices include a technical assessment. Even where they do not, fluency signals you can contribute from day one.

• ✓

  Week 4: Do 1 full mock (reasoning test + written case + presentation + behavioral). Simulating the half-day format end to end builds stamina and surfaces time-management gaps before the real assessment.

What mistakes do candidates make most?

1. Preparing with management consulting frameworks. Compass Lexecon does not use profitability trees or a 4P analysis. Forcing a generic framework onto an antitrust case signals you do not understand the role. Keep the structured habit, drop the templates.

2. Ignoring the written component. The case requires structured prose supported by data. Candidates who only practice verbal delivery underperform when asked to write a concise economic recommendation in under 90 minutes.

3. Treating regression output as decoration. The regression results in the packet are the core evidence. Skimming the numbers and jumping to qualitative reasoning misses the point. Build the same discipline you would use for charts and exhibits.

4. Quoting a number with no error bars. Whether it is an HHI delta or an overcharge, name the assumptions and the alternative explanations. A defensible estimate with stated limitations beats a precise number you cannot defend.

Related Guides

• NERA Economic Consulting case interview guide: NERA's interview format, salary data, and prep strategy
• Analysis Group case interview guide: the largest privately held econ consulting firm
• Charles River Associates case interview guide: CRA's life sciences and IP focus
• Cornerstone Research case interview guide: securities litigation and event study specialist
• Bates White case interview guide: boutique economic consulting with litigation-support focus
• Case interview math practice: build computational speed for data-heavy econ cases
• Case interview prep for career changers: moving into consulting from another quantitative field
• Consulting career path: how economic consulting progression compares to management consulting

Sources (checked June 18, 2026)

• Wall Street Oasis Compass Lexecon Interview Questions: wallstreetoasis.com/company/compass-lexecon/interview
• Wall Street Oasis Compass Lexecon Salary Data: wallstreetoasis.com/company/compass-lexecon/salary
• Glassdoor Compass Lexecon Interview Reviews: glassdoor.com/Interview/Compass-Lexecon-Interview-Questions-E368079.htm
• Glassdoor Compass Lexecon Salary Data: glassdoor.com/Salary/Compass-Lexecon-Salaries-E368079.htm
• Hacking the Case Interview, Economic Consulting Case Interview: hackingthecaseinterview.com/pages/economic-consulting-case-interview
• FTI Consulting, Compass Lexecon Recognized on the 2026 GCR 100: fticonsulting.com/about/newsroom/press-releases/fti-consulting-compass-lexecon-recognized-2026-gcr-100-list
• Global Competition Review GCR 100, Compass Lexecon profile: globalcompetitionreview.com/survey/gcr-100/26th-edition/organization-profile/compass-lexecon
• Compass Lexecon Official Site: compasslexecon.com