Portfolio Attribution Explained: What Actually Drove Your Investment Returns?

Contribution vs Attribution

Contribution explains the parts of the portfolio. Attribution explains the difference from a benchmark.

Bull Run's Six-Layer Attribution Map

Step 1: Select the Correct Benchmark

Attribution is only as good as the benchmark. The benchmark should match:

• strategic asset allocation;
• large-, mid- and small-cap exposure;
• geography and reporting currency;
• sector or factor mandate;
• total-return convention.

NSE Indices explains that a Total Return Index incorporates both price changes and dividends. Using a price-only benchmark can overstate active return.

Step 2: Reconcile Returns and Cash Flows

Use XIRR to understand the investor's money-weighted experience and time-weighted return for strategy attribution where available. External cash flows should not be mistaken for manager return.

Step 3: Calculate Holding-Level Contribution

Example:

• Beginning weight: 8%
• Holding return: 25%

For holdings bought or sold during the period, use daily or subperiod weights rather than beginning weight alone.

Contribution Is Not the Same as Holding Return

A spectacular return in a tiny position can matter less than a moderate return in a core holding.

Step 4: Group Holdings Consistently

Attribution can be run by:

• asset class;
• sector and sub-sector;
• large, mid and small cap;
• domestic and international;
• quality, value, momentum or other factors;
• core and satellite sleeves;
• direct stocks and funds;
• investment thesis or economic risk cluster.

Use the same group definitions for the portfolio and benchmark.

The Brinson Allocation Effect

A common attribution framework compares portfolio group weights with benchmark group weights.

Allocation adds value when the portfolio overweights a benchmark group that outperforms the total benchmark, or underweights one that underperforms.

Worked Allocation Example

Assume financials were 30% of the portfolio and 24% of the benchmark. The financials benchmark returned 18%, while the total benchmark returned 12%.

The financial-sector overweight added approximately 0.36 points before considering stock selection inside the sector.

The Security-Selection Effect

Selection measures whether the portfolio's securities within a group outperformed that group's benchmark return.

Worked Selection Example

Financials were 24% of the benchmark. The portfolio's financial holdings returned 22%, while benchmark financials returned 18%.

The stocks chosen inside financials added approximately 0.96 points.

The Interaction Effect

Interaction captures the combined result of overweighting or underweighting a group in which security selection also differed from the benchmark.

Using the same numbers:

Allocation + Selection + Interaction

In the example:

The result should reconcile, subject to methodology and rounding, with the group's contribution to portfolio active return.

Step 5: Attribute Market-Cap Exposure

A mixed-cap portfolio can outperform because it held more mid or small caps than its benchmark. This should be separated from stock selection.

Step 6: Attribute Factor Exposure

Review whether returns came from:

• quality;
• value;
• momentum;
• low volatility;
• size;
• dividend yield;
• state ownership;
• high or low leverage;
• growth and valuation.

A portfolio of unrelated companies can still be one concentrated factor bet.

Factor Attribution Without a Full Model

A practical investor can divide holdings into factor buckets and compare:

• weight in each bucket;
• bucket return;
• benchmark bucket weight and return;
• active contribution;
• valuation and concentration at period end.

This is less precise than regression-based factor attribution but often more interpretable.

Step 7: Attribute Currency and International Return

For international investments, separate:

• underlying market return;
• currency translation;
• fund or product tracking difference;
• fees and taxes.

A foreign portfolio can rise in local currency but fall in rupees, or vice versa.

Step 8: Attribute Cash

Cash can be strategic, temporary or accidental.

Cash detracts during strong equity markets and protects during declines. Judge it against the written policy:

• strategic emergency and goal reserve;
• tactical market timing;
• uninvested contribution;
• transaction settlement balance.

Step 9: Attribute Costs and Turnover

A strategy producing 4% gross alpha and 3% combined friction created only 1% investor-level net value before considering research time and estimation error.

Step 10: Attribute Fund Overlap

Look through mutual funds and ETFs:

A direct stock may appear to be the best contributor while much of the same company is already owned through funds. Attribution should calculate the combined economic position.

Step 11: Attribute Concentration

Calculate how much active return came from the top positions:

When more than all active return comes from one or two holdings, the remaining portfolio may have lagged. The outperformance is real but fragile.

Step 12: Separate Skill from Luck

Bull Run's Decision Attribution

Classify every meaningful active decision:

• stock selection;
• position sizing;
• sector allocation;
• market-cap allocation;
• buy timing;
• sell timing;
• rebalancing;
• cash decision;
• currency or international decision;
• portfolio simplification.

Hit rate must be combined with payoff. A minority of large winners can outweigh frequent small mistakes.

Decision Payoff Ratio

A process with 45% hit rate and 3:1 payoff can be superior to one with 70% hit rate and 0.5:1 payoff.

Worked Example 1: Outperformance Came from Small Caps

A portfolio beats its benchmark by 6%. Market-cap attribution shows 5 points came from a large small-cap overweight and only 1 point from selection.

The investor should not conclude that every chosen stock was superior. Most value came from segment allocation.

Worked Example 2: Good Stocks in the Wrong Sector

The portfolio selected better companies than the benchmark inside chemicals, but the sector underperformed and was heavily overweighted.

Selection effect is positive, allocation effect is negative and total active contribution is weak.

Worked Example 3: One Winner Explains Everything

A 7% holding triples and contributes approximately 14 points. Total portfolio active return is 10 points.

Excluding the winner, the rest of the active portfolio lagged. The investor reviews concentration and whether the result can repeat.

Worked Example 4: Cash Protected the Portfolio

During a market decline, 15% cash reduces drawdown. Cash attribution is positive relative to the equity benchmark.

The result is skill only when the cash level followed the written policy or a documented active decision, not when it was accidental.

Worked Example 5: Currency Created International Return

A foreign market is flat in local currency, but the rupee weakens. The international allocation gains in rupee terms.

Currency attribution separates this from security or market selection.

Worked Example 6: Fund Fees Erase Selection Value

An active fund's holdings beat its index before costs, but the investor's net return only matches a lower-cost alternative.

Gross selection effect exists; investor-level net value does not.

Worked Example 7: Overlap Doubles a Contributor

A major bank is owned directly and through two funds. Look-through analysis shows 12% total exposure.

The bank's contribution is larger than the direct account suggests, and so is future company-specific risk.

Worked Example 8: Rebalancing Added Value

The investor trimmed an oversized sector and added to an underweight defensive allocation. The sector subsequently corrected.

Attribution assigns the benefit to rebalancing rather than security selection.

Worked Example 9: Turnover Reduced Net Alpha

Gross active return is 5%, but turnover, spread, taxes and fees consume 3.5 points.

Decision attribution identifies implementation discipline as the improvement opportunity.

Worked Example 10: Strong Return, Weak Process

The portfolio earns 25%, but trades were undocumented, concentration exceeded policy and results depended on one theme.

Outcome attribution is positive; process attribution is weak. The investor should not scale risk merely because the year was profitable.

The Quarterly Attribution Workflow

Portfolio Attribution Worksheet

Common Attribution Mistakes

1. Using the wrong benchmark

Market-cap or sector exposure can be mistaken for skill.

2. Using a price index instead of TRI

Benchmark dividends are omitted.

3. Confusing return with contribution

A small holding's large return may contribute little.

4. Ignoring changing weights

Beginning-weight approximations can fail when turnover is high.

5. Mixing attribution methodologies

Allocation and selection effects may be defined differently.

6. Ignoring funds and direct-stock overlap

Economic contribution is understated.

7. Ignoring cash and currency

Important return sources disappear.

8. Reporting gross alpha only

Costs and taxes may erase value.

9. Calling one lucky winner a repeatable process

Concentration can dominate the result.

10. Doing attribution without changing decisions

Analysis should improve sizing, selection and implementation.

How Bull Run Features Fit Attribution

Use the Bull Run watchlist to document candidate theses before outcomes are known.

Use Bull Run Compare to evaluate whether selection value came from stronger fundamentals or a temporary valuation move.

The Stock Battle tool can compare decisions competing for one portfolio role. Smart Screeners can test whether successful selections came from a repeatable rule.

Primary Official and Research Sources

• CFA Institute Research Foundation: Performance Attribution literature review
• CFA Institute Research Foundation: currency management and performance attribution
• NSE Indices: Total Return Index concept
• SEBI: Information Ratio disclosure for mutual-fund schemes
• SEBI: performance benchmarking and reporting by portfolio managers
• Bull Run data sources and coverage policy