Concentration Risk and Large Exposures: A Banker's Guide for the IIBF Exam

For bankers preparing for the IIBF Risk in Financial Services certification, few topics carry as much practical weight as concentration risk. When a bank's exposures cluster around a single borrower, group, sector, or geography, a localised shock can threaten solvency, which is exactly why Basel and the RBI have built strict guardrails around large exposures. This guide breaks down the concept, the regulatory framework, and the management techniques you must know for the exam and the job.

What Is Concentration Risk?

Concentration risk is the risk of loss arising from an excessive build-up of exposure to a single counterparty, a group of connected counterparties, or to counterparties that share common risk drivers such as the same industry, region, or collateral type. It is a second-order form of credit risk: individually each loan may be sound, but their correlated behaviour means they can deteriorate together.

Concentration typically appears in several forms:

• Single-name (idiosyncratic) concentration — too much exposure to one borrower or connected group.
• Sectoral concentration — heavy lending to one industry, such as infrastructure, real estate, or NBFCs.
• Geographic concentration — exposures tied to one state or region vulnerable to a common event like drought or industrial decline.
• Collateral and funding concentration — reliance on one type of security or a narrow set of depositors.

The danger is non-linear. A diversified portfolio absorbs idiosyncratic defaults, but concentrated books expose the bank to tail events where one failure cascades. This is why concentration risk sits at the heart of both Pillar 1 large-exposure caps and Pillar 2 supervisory review. If you want to test your grasp of these distinctions, the practice sets at iibf.store/tests include scenario questions on portfolio concentration.

The Basel Large Exposures Framework

The Basel Committee's Large Exposures (LEX) framework, finalised in 2014 and effective from 2019, is the global standard limiting single-name concentration risk. Its core rule is simple to state and central to the exam.

• The 25% cap: A bank's sum of all exposure values to a single counterparty or group of connected counterparties must not exceed 25% of the bank's available eligible Tier 1 capital.
• The G-SIB tightening: For exposures between two global systemically important banks (G-SIBs), the limit is reduced to 15% of Tier 1 capital to curb interconnectedness.
• The reporting trigger: Any exposure of 10% or more of Tier 1 capital qualifies as a "large exposure" and must be reported to the supervisor.

Key design choices matter. The denominator shifted from total capital to Tier 1 capital, a higher-quality, more loss-absorbing base. "Connected counterparties" are grouped using control and economic-interdependence tests, so a parent and its subsidiaries count as one. Credit risk mitigation such as eligible guarantees and collateral can shift exposure from the obligor to the protection provider, but that may create a new concentration against the guarantor. Understanding how the LEX framework interacts with capital adequacy is core CAIIB material; the CAIIB course covers the capital-and-risk linkages in depth.

RBI's Large Exposures Framework in India

The RBI implemented its own Large Exposures Framework (LEF) for scheduled commercial banks, aligned with Basel and applied to exposures on a fully loaded basis. It is the version Indian bankers must know cold.

• Single counterparty: Sum of exposures to one counterparty must not exceed 20% of the bank's Tier 1 capital, which the board may raise to 25% in exceptional cases.
• Group of connected counterparties: Capped at 25% of Tier 1 capital.
• Reporting: Exposures of 10% or more of Tier 1 capital are large exposures and reported to the RBI.

Note that India's single-borrower base limit (20%) is tighter than the plain Basel 25%, reflecting the RBI's conservative stance. The LEF replaced the older single/group borrower limits that were expressed as a percentage of capital funds. The framework also addresses interconnectedness through the economic-interdependence criteria and brings non-centrally-cleared and certain interbank exposures into scope. Banks must additionally observe internal sectoral and prudential sub-limits set by their boards as part of Pillar 2. For current capital-related reference points and policy rates that feed into these calculations, see the RBI rates resource, and track regulatory updates via IIBF news.

Measuring and Managing Concentration Risk

Beyond hard caps, banks measure and manage concentration risk through statistical tools and governance. Examiners expect you to know both the metrics and the mitigants.

Measurement tools

• Herfindahl-Hirschman Index (HHI): the sum of squared exposure shares; a higher value signals a more concentrated, riskier portfolio.
• Gini coefficient and concentration ratios: capture inequality in exposure distribution, such as the share held by the top 10 borrowers.
• Stress testing and sensitivity analysis: model the impact of a sector downturn or a single large default on capital.

Management techniques

• Prudential limits: board-approved single-borrower, group, and sectoral sub-limits operating below regulatory ceilings.
• Diversification: deliberately spreading exposures across borrowers, sectors, and geographies.
• Risk transfer: loan syndication, securitisation, credit default swaps, and guarantees to offload excess exposure.
• Capital buffers: holding Pillar 2 capital add-ons where supervisors judge residual concentration material.

Effective management also depends on accurate counterparty grouping and timely monitoring dashboards. To reinforce these terms before the exam, the term-matching drill at iibf.store/games/match is a quick, active-recall way to lock in definitions like HHI, connected counterparties, and Tier 1 capital.

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: Lock In Your Concentration Risk Knowledge

Mastering concentration risk means knowing the forms it takes, the Basel 25% and G-SIB 15% caps, the RBI's 20%/25% Tier 1 limits, and the measurement and mitigation toolkit. These are high-yield areas in the Risk in Financial Services paper and recur in real supervisory work. Put your understanding to the test with the focused question banks at iibf.store/tests, and deepen the underlying capital and risk concepts through the CAIIB course. For more exam-focused explainers, browse the iibf.store blog.