Portfolio Management interview preparation

Questions

100

Traced to a firm

40

Firms

24

Updated

September 2026

Asked at

All firmsBLBlackRock4Vanguard4WMWellington Management4Amundi3ACAQR Capital Management3Neuberger Berman3SCSchroders3Man Group2MSCI2Northern Trust2AllianceBernstein1Apollo Global Management1Blackstone1BMBNY Mellon1Carlyle Group1Fidelity Investments1Goldman Sachs1Invesco1Millennium Management1MSMorgan Stanley1NUNuveen1PIMCO1SSState Street1TPTPG1

Topic

All topicsPortfolio theory5Factor models8Asset allocation11Rebalancing3Portfolio construction7Benchmarks and tracking error5Performance measurement8Risk management6Fixed income and LDI5Currency and global3Implementation and costs5Active versus passive6India markets7Brainteasers5Career and fit16

Level

AnyCoreIntermediateHard

Type

AnyTechnicalCaseMarket viewFitBrainteaser

1. 035How do you choose a benchmark for a mandate, and what makes a benchmark bad?Benchmarks and tracking errorCorephone / first roundAsset managementInstitutional asset management

   Say this

   A good benchmark is investable, unambiguous, specified in advance, and it represents the manager's actual opportunity set. A bad one is either unachievable, like a fixed 8 percent hurdle, or so different from the portfolio that the excess return measures style rather than skill.

   Then walk it

   1. The standard criteria, from Bailey: unambiguous, investable, measurable, appropriate to the manager's style, reflective of current investment opinion, specified in advance, and owned by the manager in the sense that they accept it.
   2. Investable is the one most often breached. A benchmark including names that cannot be bought in size, or an index with a 15 percent single-stock weight that breaches the fund's diversification rules, sets the manager an impossible task.
   3. Appropriate to the style matters most for attribution. Measure a small cap value manager against a broad large cap index and the excess return is mostly the size and value factor, not the manager. You will fire them for style and hire the next one at the wrong point in the cycle.
   4. Bad benchmark type one, absolute hurdles: 'cash plus 5 percent' is fine as an objective but useless as a benchmark, because it gives no information about whether the manager did well in the environment they faced.
   5. Bad benchmark type two, peer group medians. They are not investable, they are survivorship biased, they are only known after the fact, and they encourage herding. Useful as context, wrong as a benchmark.
   6. In practice I would use a market index matched to the opportunity set, with a custom or blended index where the mandate spans regions or asset classes, and I would state the currency hedging convention in the benchmark definition. Hedged versus unhedged is worth several percent a year and it is astonishing how often that is left vague.

   Where candidates lose it

   Listing the textbook criteria without saying which ones actually get breached. Concrete failures are what earn the marks: peer medians, absolute hurdles, style mismatch, and an unspecified currency hedging convention. That last one is a detail interviewers in global mandates notice immediately.

   Expect next

   • How would you benchmark a multi-asset fund with no natural index?
   • Should the benchmark be hedged or unhedged?
   • What is wrong with a peer group benchmark?
2. 036What is the difference between ex-ante and ex-post tracking error, and why do they diverge?Benchmarks and tracking errorIntermediatetechnicalMSCIFinancial Tools · Monterrey · 2013

   Say this

   Ex-post is the realised standard deviation of active returns, computed from the return series. Ex-ante is a forecast from a risk model applied to today's holdings. They diverge because the model uses stale covariances, because the portfolio changed during the measurement window, and because realised risk includes events the model did not have.

   Then walk it

   1. Ex-post is simple arithmetic: take portfolio return minus benchmark return each period, take the standard deviation, annualise by multiplying by the square root of the number of periods per year. It describes history and it needs 36 or more observations to mean much.
   2. Ex-ante takes the current active weight vector and computes the square root of w transpose sigma w using a factor risk model. It describes today's portfolio and it updates daily, which is why risk systems report it.
   3. Divergence reason one, the covariance matrix. Risk models estimate it over a long window, sometimes with exponential weighting, so they lag regime changes. Going into February 2020, ex-ante tracking error was low everywhere and realised tracking error exploded.
   4. Reason two, the portfolio moved. Ex-post over three years reflects every portfolio you held during those three years, including a different style and different sizes. Ex-ante is a snapshot.
   5. Reason three, model incompleteness. If your active risk comes from an exposure the model does not have a factor for, say a specific commodity input or a single regulatory event, ex-ante will report it as small specific risk while realised outcomes show it was the dominant bet.
   6. So I would use them for different jobs. Ex-ante to manage the portfolio and to police the tracking error budget in advance, ex-post to evaluate what actually happened, and I would watch the ratio between them as a model diagnostic. Persistently realising 6 percent while forecasting 3 means the risk model is missing the real bet.

   Where candidates lose it

   Giving one formula and treating the two as interchangeable. The point of the question is that a risk system's number and the performance report's number will not match, and a portfolio manager has to be able to explain why to a client. Also get the annualisation right: multiply by the square root of the frequency, do not divide.

   Expect next

   • Which one would you put in a client report?
   • What does it mean if realised is persistently double the forecast?
   • How many observations do you need for ex-post to be meaningful?

   Reported by candidates at MSCI (Financial Tools, Monterrey, 2013). Source: Wall Street Oasis.

3. 037How would you budget tracking error across a portfolio?Benchmarks and tracking errorHardsuperdayInstitutional asset managementRisk management

   Say this

   Treat it like a capital budget. The mandate gives you a total active risk allowance, and you allocate it to the decisions with the highest expected information ratio, remembering that risk adds in quadrature rather than linearly so diversified bets are cheap.

   Then walk it

   1. Start from the total: say the mandate allows 3 percent tracking error. Decompose the sources, asset allocation tilts, country and sector bets, stock selection, currency, and any manager selection risk if it is a fund of funds.
   2. Allocate by expected information ratio, not by conviction. If stock selection has a long-run IR of 0.4 and tactical allocation has 0.15, most of the budget belongs in stock selection, and that is an argument about process, not about this month's view.
   3. Use the quadrature point, because it is the technical content of the question. Three uncorrelated 1.5 percent sources give a total of about 2.6 percent, not 4.5 percent. So spreading the budget across genuinely independent decisions buys you more expected return per unit of total active risk.
   4. Which means correlation between active bets is the thing to police. An overweight to technology and an overweight to growth and an underweight to duration are one bet, and they will consume the budget three times over while delivering one payoff.
   5. Leave headroom. Run at perhaps 70 to 80 percent of the limit in normal conditions, because a volatility spike will raise your ex-ante tracking error without you trading, and being forced to cut positions to cure a breach is the worst possible reason to trade.
   6. Then monitor it prospectively and review the allocation, not just the level. If realised attribution says the 1 percent you spent on tactical asset allocation has produced nothing over five years, the right response is to move that budget to where the evidence is, not to try harder.

   Where candidates lose it

   Treating the budget as additive and dividing it up in straight lines. Risk adds in quadrature, so the diversification between active bets is the whole game. Also mention headroom, because breaching a tracking error limit on a volatility spike and being forced to trade is a real and unglamorous way to lose money.

   Expect next

   • How would you split the budget between allocation and selection?
   • What do you do when a volatility spike breaches the limit?
   • How do you measure correlation between active bets?
4. 038What is the fundamental law of active management, and what does it tell you to do?Benchmarks and tracking errorHardsuperdayQuantitative asset managementAsset management

   Say this

   Information ratio is roughly skill times the square root of breadth. So a modest edge applied to many independent decisions beats a strong edge applied to a handful, and it tells you to industrialise breadth rather than hunt for a bigger insight.

   Then walk it

   1. Grinold's formula: IR equals the information coefficient times the square root of the number of independent bets per year. The generalised version multiplies by a transfer coefficient for constraints.
   2. Put numbers on it, because that is what makes it real. An information coefficient of 0.05, which is a barely detectable edge, applied to 1,000 independent decisions a year gives an IR of about 1.6. An IC of 0.2, a genuinely good stock picker, across 10 decisions gives about 0.63. The mediocre systematic process wins.
   3. That single comparison explains the existence of quantitative investing, and it also explains why concentrated fundamental funds have high dispersion of outcomes: low breadth means luck dominates over any realistic evaluation period.
   4. The word doing the work is 'independent'. Two hundred positions that all express one macro view have breadth of one. Overstating breadth is the most common abuse of the formula, and it is why a sector fund with 80 names is not diversified.
   5. The transfer coefficient is the second practical lesson. Long-only, position limits and turnover caps typically cut realised IR to half of theoretical, so relaxing the most binding constraint can be worth more than improving the signal.
   6. The limitations I would name: it assumes bets are independent and that IC is stable, it ignores costs, and breadth cannot be increased indefinitely because higher frequency means higher turnover and costs eat the gain. So it is a way of thinking about where to invest research effort, not a formula to trade off.

   Where candidates lose it

   Quoting the formula without the numerical comparison and without stressing independence. The insight only lands when you show that a tiny edge times high breadth beats a large edge times low breadth. And if you claim breadth of 500 for a portfolio with one macro theme, an interviewer will take the answer apart.

   Expect next

   • How would you count breadth for a macro fund?
   • So why do concentrated funds exist at all?
   • What limits how far you can push breadth?
5. 039What is active share, and how is it different from tracking error?Benchmarks and tracking errorIntermediatetechnicalAsset managementFund selection

   Say this

   Active share measures how different the holdings are, the sum of absolute differences from benchmark weights divided by two. Tracking error measures how differently the returns behave. You can have high active share with low tracking error, and that distinction tells you what kind of active risk a manager is taking.

   Then walk it

   1. Active share is a holdings-based, forward-looking measure that needs no return history. Tracking error is returns-based and needs a series, or a risk model to forecast it. That alone makes active share useful for a new fund.
   2. The four quadrants from Cremers and Petajisto are the point of the question. High active share with low tracking error is diversified stock picking, lots of small differentiated bets. Low active share with high tracking error is factor or sector betting, a portfolio that looks like the index but is timing something. High on both is concentrated stock picking. Low on both is closet indexing.
   3. Closet indexing is the commercial reason anyone measures it. A fund with 30 percent active share charging 90 basis points is charging roughly 300 basis points on the part that is actually active, which regulators in Europe have pursued as consumer harm.
   4. The evidence on active share and performance is much weaker than the original paper suggested. Later work found the result is largely explained by benchmark choice and by a small cap tilt. So I would use active share as a description of what the manager does, not as a predictor of what they will earn.
   5. It is also gameable and benchmark-dependent. Change the benchmark to a broader index and active share rises without the portfolio changing at all, which is why it should always be quoted against the stated benchmark.
   6. Practically I would look at both plus a factor decomposition. Active share tells me whether I am paying for differentiation, tracking error tells me the risk of the differentiation, and the factor model tells me whether the differentiation is anything other than a style tilt.

   Where candidates lose it

   Treating the two as measuring the same thing on different scales. The interviewer wants the four quadrants and the insight that low active share with high tracking error means factor bets rather than stock picking. Overclaiming that high active share predicts outperformance is also a trap, because the follow-up literature does not support it.

   Expect next

   • What active share would you expect from a concentrated fund?
   • Does high active share predict returns?
   • How would you spot a closet indexer from returns alone?

Firm tags come from public, anonymous candidate reports on Wall Street Oasis: strong signal, not sworn testimony. Firms are named as the places a question was reported, not as partners of Fin Maverick. Answers are written for this page to show how to think out loud; they are not scripts to recite.