Asset Liability Management (ALM): Duration Gap & NII Sensitivity for CAIIB BFM

Asset liability management is the single most testable, score-deciding chapter in CAIIB BFM Module C — and the one where most aspirants quietly lose marks. The questions look numerical and intimidating, but they reward a clear head and three or four formulas you can recall under pressure. This guide rebuilds the entire topic from first principles: what ALM actually does, how rate-sensitive gap analysis works, how duration gap measures economic-value risk, and how a single +100 basis point rate shock flows through to net interest income (NII). By the end you will be able to read a balance sheet, classify items, compute the gap and the duration gap, and predict the direction of the NII impact in seconds.

If a particular step feels heavy on the first read, watch the class above and then return to the worked example below. The maths is far gentler once you have seen it solved on a board.

What asset liability management actually solves

Asset liability management is the discipline of managing the financial risks that arise from timing mismatches between a bank's assets and its liabilities. The core of banking is simple in one line: banks borrow money (deposits and borrowings, which are liabilities) and lend it out (loans and investments, which are assets). The complication is that these two sides almost never mature, or reprice, on the same clock.

Picture a bank holding long-term, fixed-rate housing loans funded largely by short-term deposits. When interest rates rise, the deposits reprice quickly — savers demand more — while the loan yields stay fixed for years. The interest expense climbs faster than interest income, and the margin is squeezed. The mirror image is equally dangerous: when rates fall, a bank funded by long-dated, high-cost deposits but holding short-term assets sees its income drop faster than its cost.

This is the precise problem ALM tackles. Through a structured framework, the bank's Asset Liability Committee (ALCO) works to:

• Monitor rate-sensitive assets (RSA) and rate-sensitive liabilities (RSL) across maturity buckets.
• Quantify maturity gaps and duration gaps.
• Estimate the impact on NII and on economic value under different rate scenarios.
• Manage liquidity risk, interest-rate risk and market risk together, not in silos.
• Stay aligned with RBI guidelines and Basel III standards.

Keep this framing in mind throughout: ALM is not a compliance chore bolted onto the balance sheet. It is how a bank protects both its income next quarter and its net worth over the cycle.

Rate-sensitive assets vs rate-sensitive liabilities

Every ALM calculation starts by sorting the balance sheet by repricing frequency — how soon each item's interest rate can change, usually within a one-year horizon.

Rate-sensitive assets (RSA) are assets that reprice within the chosen window. Typical examples include:

• Floating-rate loans and advances linked to MCLR, the repo rate or an external benchmark.
• Short-dated treasury bills and securities maturing soon.
• Money-market investments and call lending.

Rate-sensitive liabilities (RSL) are liabilities that reprice in the same window, such as:

• Short-term wholesale and bulk deposits nearing maturity.
• Certificates of deposit (CDs) and short-tenor borrowings.
• Borrowings from the RBI's liquidity windows.

A fixed-rate bond held to maturity is not rate-sensitive in this sense — its coupon does not reset. That single distinction is a favourite of CAIIB examiners, so anchor it firmly.

The headline metric is the repricing gap:

Gap = RSA − RSL

A positive gap means more assets than liabilities reprice in the period, so rising rates boost NII. A negative gap means liabilities reprice faster, so rising rates hurt NII. Commit the direction to memory now — half the MCQs in this module are simply testing whether you know which way the gap points.

Duration gap: measuring economic-value risk

Simple gap analysis counts how many items reprice, but it says nothing about how much their market value moves. That is the job of duration. Duration is the weighted-average time, in years, to receive a bond's cash flows, and it doubles as a measure of price sensitivity to interest-rate changes.

Macaulay duration is defined as:

D = Σ [ t × PV(CF_t) ] / Bond Price

where t is the time period and PV(CF_t) is the present value of the cash flow in that period.

Modified duration converts this into a percentage price change for a 1% (100 bps) move in yield:

Modified Duration = D / (1 + y)

where y is the yield to maturity. A bond with a modified duration of 4 loses roughly 4% of its value if yields rise by 100 bps.

Scaling this idea up to the whole balance sheet gives the duration gap:

Duration Gap = D_A − (L/A) × D_L

where D_A is the weighted-average duration of assets, D_L is the weighted-average duration of liabilities, and L/A is the ratio of liabilities to assets (a leverage adjustment). A positive duration gap means asset values fall faster than liability values when rates rise, eroding the economic value of equity. A negative duration gap benefits the bank if rates fall. The ALCO deliberately targets a duration gap that matches its interest-rate outlook and risk appetite.

NII sensitivity under a +100 basis point shock

Net interest income (NII) is interest earned on assets minus interest paid on liabilities. Stress-testing NII under a standard +100 bps rate shock reveals how exposed the bank's earnings are. The quick income approximation is:

ΔNII ≈ Gap (RSA − RSL) × ΔR

where ΔR is the rate change in decimal form (+100 bps = +0.01). For the economic-value angle, use the duration-based version:

ΔEV ≈ −Duration Gap × Total Assets × ΔR

The intuition: a bank with a positive gap of ₹500 crore gains about ₹5 crore of NII in the near term if rates rise 100 bps. A bank with a negative gap of ₹300 crore loses about ₹3 crore of NII under the same shock. The two formulas can point in opposite directions — income up, economic value down — and recognising that tension is exactly what separates a top scorer from the rest.

Traditional gap analysis, step by step

In practice, banks do not use a single one-year bucket. They slot every item into time bands and analyse each one. A workable sequence is:

1. Classify items into repricing buckets — for example overnight to 1 month, 1–3 months, 3–6 months, 6–12 months, and beyond 12 months (treated as non-sensitive).
2. Compute the gap per bucket: Gap_t = RSA_t − RSL_t.
3. Build the cumulative gap by running totals across buckets, which shows when repricing dominance shifts from assets to liabilities.
4. Estimate the NII impact: multiply each gap by the assumed rate change.
5. Monitor over time: refresh the buckets, compare actual against forecast, and report to the ALCO.

The method is intuitive and board-friendly, which is its strength. Its weakness is that it ignores embedded options, reinvestment risk and the non-linear way prices react to large rate moves — limitations the duration framework partly fixes.

Comparing the two ALM frameworks

Examiners love a question that asks you to contrast simple gap analysis with duration gap. Keep this table in your head.

For deeper revision of the same ideas from the risk angle, pair this with our companion explainer on CAIIB BFM risk management with duration gap and VaR demystified, which extends the duration story into value-at-risk. Once Module C is solid, broaden your treasury context with our guide to the Liquidity Adjustment Facility for CAIIB Central Banking, since LAF operations directly shape the short-term rates that drive your gap.

Worked numerical example you can reuse

Numericals in this module follow a predictable shape. Master this one and you can handle almost any variant the paper throws at you.

Scenario — Bank ABC:

• Total assets: ₹10,000 crore
• Total liabilities: ₹9,000 crore
• Rate-sensitive assets (next 12 months): ₹4,500 crore
• Rate-sensitive liabilities (next 12 months): ₹4,000 crore
• Weighted-average duration of assets (D_A): 3.5 years
• Weighted-average duration of liabilities (D_L): 2.0 years

Step 1 — Simple gap (1-year bucket):
Gap = RSA − RSL = ₹4,500 cr − ₹4,000 cr = ₹500 crore (positive).

Step 2 — Duration gap:
Duration Gap = D_A − (L/A) × D_L = 3.5 − (9,000 / 10,000) × 2.0 = 3.5 − 1.8 = 1.7 years (positive).

Step 3 — NII impact under +100 bps (income view):
ΔNII ≈ Gap × ΔR = ₹500 cr × 0.01 = +₹5 crore — a near-term improvement.

Step 4 — Economic-value impact under +100 bps (duration view):
ΔEV ≈ −Duration Gap × Assets × ΔR = −1.7 × ₹10,000 cr × 0.01 = −₹17 crore on a mark-to-market basis.

Reading the result: Bank ABC has a positive gap, so if rates rise its short-term NII improves. But the positive duration gap means its longer-dated asset values fall faster than its liability values, so the economic value of equity declines. This is the classic ALM trade-off — protecting income today can quietly expose net worth tomorrow, which is exactly why the ALCO watches both numbers.

ALCO governance and RBI expectations

The Asset Liability Committee (ALCO) is the senior body that owns ALM. It is usually chaired by the Managing Director or Chief Financial Officer, with the heads of treasury, risk, finance and the major business lines around the table. Its core mandate is to:

• Set ALM policy, limits and tolerance levels for interest-rate and liquidity risk.
• Review gap positions and duration metrics on a regular cycle.
• Run stress tests and scenario analysis across a range of rate shocks.
• Approve hedging strategies and any use of derivatives.
• Ensure compliance with RBI norms, including the liquidity coverage ratio (LCR) and net stable funding ratio (NSFR).
• Report its findings to the board and the risk-management committee.

On the regulatory side, the RBI — drawing on Basel III — expects banks to maintain a robust interest-rate risk in the banking book (IRRBB) framework, conduct periodic IRRBB assessments, document their ALM policies and stress-test methodologies, and keep transparent board oversight. For time-sensitive specifics such as current ratio thresholds or reporting frequencies, always confirm against the latest released RBI master direction rather than relying on memory, because these are revised from time to time. You can cross-check syllabus weightage and the institute's own framing on the official IIBF website.

A focused 5-day study plan for ALM

ALM rewards spaced, hands-on practice far more than passive reading. Use this compact plan in the run-up to the exam.

1. Day 1 — Foundations: nail the definitions of RSA, RSL, gap and repricing; solve 8–10 simple gap problems; skim the RBI material on interest-rate risk.
2. Day 2 — Duration: derive Macaulay and modified duration, compute duration for three or four bonds, and work at least five duration-gap problems.
3. Day 3 — NII sensitivity: drill the income and economic-value formulas under ±50, ±100 and ±200 bps shocks; re-solve the Bank ABC example until it is automatic.
4. Day 4 — Governance and liquidity: revise the ALCO structure, LCR, NSFR and IRRBB reporting; attempt 10–12 conceptual MCQs.
5. Day 5 — Full mock and review: take a timed Module C mock, analyse every error, and commit the key formulas to memory.

Turn each day's theory into marks straight away with our CAIIB mock tests with bilingual explanations, and use the CAIIB matching games for 60-second recall drills on formulas and definitions. The full chapter sequence sits inside the Bank Financial Management syllabus and free classes, while the wider CAIIB exam hub ties Module C to the rest of your preparation. You can also browse every CAIIB exam guide on the blog to plan the modules around Module C.

Common mistakes that cost marks

• Confusing the two gaps. The repricing gap drives income; the duration gap drives economic value. They answer different questions and can move in opposite directions.
• Mis-classifying a fixed-rate bond as rate-sensitive. If the coupon does not reset within the window, it is not an RSA.
• Forgetting the leverage term. Duration gap is D_A − (L/A) × D_L, not simply D_A − D_L. Dropping the L/A ratio is a frequent silent error.
• Sign slips on ΔEV. A positive duration gap with rising rates gives a negative change in economic value — mind the minus sign in the formula.
• Decimal errors on the shock. 100 bps is 0.01, not 0.1. A misplaced decimal turns ₹5 crore into ₹50 crore.
• Ignoring optionality. Prepayment options on loans and premature-withdrawal options on deposits change effective duration; flag this awareness in descriptive answers.

Frequently asked questions

What is the difference between gap analysis and duration gap?

Gap analysis counts repricing events over fixed time buckets and estimates the short-term impact on net interest income. Duration gap incorporates time-weighted cash flows and price sensitivity, so it captures the change in the bank's economic value of equity. In short, gap analysis is an earnings view while duration gap is a net-worth view, and a complete ALM picture needs both.

Can a bank have both a positive gap and a positive duration gap?

Yes, and it is common. A positive gap (RSA greater than RSL) means NII benefits when rates rise, while a positive duration gap means assets are longer-duration than liabilities, so economic value falls when rates rise. The two coexist because they measure different risks over different horizons, which is precisely the trade-off the ALCO manages.

How often does the ALCO meet?

Most banks convene the ALCO monthly, with larger or more volatile institutions meeting fortnightly or even weekly during stressed periods. The exact cadence is set by the bank's internal governance policy within the broader supervisory expectation of robust monitoring. For the current regulatory position, always confirm against the latest released RBI guidance.

What is the RBI's stance on ALM and interest-rate risk?

The RBI, in line with Basel III, expects banks to run a sound interest-rate risk in the banking book (IRRBB) framework, stress-test regularly, and maintain strong board oversight of ALM. Specific disclosure formats and thresholds are periodically updated, so treat any exact figure as time-sensitive and verify it against the latest released RBI master direction or notification.

How are embedded options handled in ALM?

Embedded options such as loan prepayments, deposit premature withdrawals and interest-rate caps or floors alter the effective duration and the repricing profile of an instrument. Most CAIIB questions focus on vanilla bonds and floating-rate loans, but you should mention optionality where relevant. Recognising that options make duration behave non-linearly is enough to earn the marks at this level.

Which ALM framework is most exam-relevant for CAIIB BFM?

Expect a balanced mix. Simple gap analysis tests conceptual clarity, duration gap tests advanced numerical reasoning, and ALCO governance tests your regulatory knowledge. Practising all three is the safest strategy because examiners deliberately test breadth across Module C rather than a single technique.

Final word

Asset liability management is the heartbeat of prudent banking, not a box-ticking exercise. Once you can classify a balance sheet, compute the gap and the duration gap, and trace a +100 bps shock through to both NII and economic value, this module shifts from your weakest to one of your strongest. Work the Bank ABC example until it is muscle memory, drill the formulas daily, and confirm any time-sensitive number on the official IIBF and RBI notifications. Put in the repetitions and these marks are yours.

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