Concentration Risk in Banking: CAIIB RFS Guide 2026

Concentration risk is one of the most heavily tested ideas in the Risk in Financial Services (RFS) paper. And a recurring favourite for CAIIB candidates preparing in 2026. In simple terms.

It is the danger a bank faces when too much of its exposure is bunched into a single borrower. Sector, geography or instrument. Mastering how concentration risk is measured.

Limited. Reported will help you answer both the theory. Numerical questions that examiners love to set on this topic.

What concentration risk means in banking

At its core. Concentration risk arises whenever a portfolio is not adequately diversified. So that a single adverse event can inflict outsized losses.

A bank that lends 40% of its book to one industry. Or stakes a huge limit on one corporate group. Has effectively put many eggs in one basket.

When that basket falls, capital can be wiped out quickly.

Examiners expect you to recognise the main forms this risk takes:

• Single-name (obligor) concentration — excessive exposure to one borrower or connected group.
• Sectoral concentration — heavy lending to one industry such as real estate. Power or gems and jewellery.
• Geographic concentration — overdependence on one region whose economy can turn together.
• Collateral and product concentration. Reliance on one type of security or one funding instrument.

Crucially, concentration risk is not a separate silo. It amplifies credit, market and liquidity risk alike, which is why the Basel framework treats it as a Pillar 2 concern that supervisors review under the ICAAP. For the foundations of these risk types, the structured modules in the CAIIB course are a reliable starting point before you attempt full-length mocks.

How banks measure and quantify concentration risk

You will not score well on this paper unless you can name the standard yardsticks. Concentration is rarely "felt"; it is calculated. The most examinable measures include:

• Herfindahl-Hirschman Index (HHI) — the sum of squared exposure shares. A higher HHI signals a more concentrated, riskier book.
• Gini coefficient — captures inequality in exposure distribution across borrowers.
• Concentration ratio — the share of the top 5, 10 or 20 exposures in total credit.
• Large-exposure metrics — exposures above a threshold of Tier 1 capital. Flagged under RBI's Large Exposures Framework.

Why diversification scores matter

These indices feed directly into a bank's internal capital assessment. A high HHI means the bank should hold an add-on of capital under Pillar 2 to cushion the lumpiness. In the RFS exam, you may be handed exposure shares and asked to compute an HHI, so practise the arithmetic until it is automatic. The timed quizzes on the iibf.store tests page are ideal for drilling this kind of calculation under exam-like pressure.

Remember the operational-risk connection too: when concentration triggers a default cluster. The resulting losses are logged as loss events. Classified by type, exactly as the Basel taxonomy prescribes.

The RBI Large Exposures Framework

For the Indian context. The single most important rule set governing concentration risk is the RBI Large Exposures Framework (LEF). It caps how much a bank may lend to a counterparty or a group of connected counterparties. Expressed as a percentage of eligible Tier 1 capital.

Key features you should memorise in principle (always confirm the live thresholds. As RBI revises them):

• A ceiling on the sum of all exposures to a single counterparty.
• A higher, separate ceiling for a group of connected counterparties.
• Tighter limits for exposures to global systemically important banks.
• Mandatory aggregation of on- and off-balance-sheet exposures, including derivatives.

The LEF complements sectoral caps and internal prudential limits that boards set voluntarily. Together they form the first line of defence against a single shock dismantling the balance sheet. To keep the exact percentages and any recent circular changes at your fingertips, bookmark the live RBI rates and limits reference and the curated IIBF news updates, both refreshed regularly for exam candidates.

Linking concentration risk to the Basel operational-risk engine

Concentration risk does not live in isolation from operational risk. When concentrated exposures sour. The workout.

Litigation. Recovery activity that follows generates operational losses that banks must capture under the Basel framework. Under the Standardised Approach.

A bank's internal loss history directly scales its capital charge.

How loss data flows into capital

Three governance tools feed the engine that decides this charge:

• RCSA (Risk and Control Self-Assessment). Managers score the likelihood and impact of control failures.
• KRIs (Key Risk Indicators). Early-warning metrics such as breach counts or limit overshoots.
• Internal loss data — a clean, multi-year history of actual losses.

This loss history drives the Internal Loss Multiplier, which adjusts the standardised capital charge up or down depending on a bank's track record. A bank whose concentration limits fail repeatedly will accumulate losses, push its multiplier higher, and end up holding more capital — a direct financial penalty for poor diversification. You can reinforce these linkages with the rapid-recall drills on the match-the-concept game, which is surprisingly effective for cementing framework vocabulary.

Managing and mitigating concentration risk

Knowing the theory is not enough. The RFS paper rewards candidates who can describe practical mitigation. Banks deploy a layered toolkit to keep concentration risk inside appetite:

• Prudential exposure limits — board-approved caps per borrower, group, sector and rating bucket.
• Portfolio diversification — deliberately spreading new lending across uncorrelated sectors and regions.
• Risk transfer — using loan sell-downs. Securitisation and credit default protection to shed lumpy exposures.
• Stress testing. Modelling how a downturn in one concentrated sector would erode capital.
• Capital add-ons — holding extra Pillar 2 buffers proportionate to the measured HHI.

Equally important is monitoring. Exposure dashboards, limit-utilisation alerts and periodic concentration reports to the risk committee turn a static policy into a living control. When a limit is breached, escalation and remediation must follow promptly, and the breach itself becomes a KRI data point. For broader revision across all RFS themes, the explainer library on the iibf.store blog ties these mitigation tools back to the wider risk syllabus.

For authoritative guidance, refer to the official resources of the Reserve Bank of India and the Indian Institute of Banking & Finance.

Frequently Asked Questions

Conclusion: Turn concentration risk into easy marks

Concentration risk rewards candidates who can move fluently between definitions, measurement (especially HHI), the RBI Large Exposures Framework, and the operational-risk capital link. Lock these four pillars down and the RFS questions become predictable marks. Put your knowledge to the test with a full-length mock on the iibf.store tests page, and build complete syllabus coverage through the structured CAIIB course so you walk into the 2026 exam confident and well-prepared.