# Beyond credit: market, operational and interest-rate risk in the banking book
In March 2023, Silicon Valley Bank did not fail because borrowers stopped repaying loans. It failed because interest rates rose fast, the market value of its bond portfolio collapsed, and depositors fled. Zero defaults. A textbook credit book. And yet the bank was gone in 48 hours.
That is the lesson. Credit risk gets the headlines, but market risk, operational risk, and interest-rate risk in the banking book (IRRBB) sink banks just as often. This lesson dissects all three: how they build, how regulators charge capital against them, and what a diligence analyst actually checks.
First, a distinction that governs everything.
Same bond can sit in either book, and the accounting differs sharply. SVB parked much of its bond portfolio in "held to maturity," so paper losses did not hit reported earnings until it was forced to sell. This gap between accounting value and market reality is where risk hides.
IRRBB is the risk that changing interest rates erode the economic value or the earnings of the banking book. Banks borrow short (deposits) and lend long (mortgages). When rates jump, the cost of deposits reprices fast while the mortgage still earns its old low coupon. Margin gets squeezed. Simultaneously, the present value of those long fixed-rate assets drops.
Two lenses regulators use:
Imagine a simplified bank with a single 10-year fixed-rate loan worth 100 (face) and a 1-year deposit funding it. Rates rise 200 basis points (2 percentage points). The rough price change on a fixed-rate instrument is:
Price change ≈ -Duration × Δ yield
For the 10-year loan, modified duration ≈ 8
Δ EVE on assets ≈ -8 × 0.02 × 100 = -16The short deposit barely moves (duration near 1, so about -0.2). Net EVE hit: roughly -15.8 on a 100 asset base. If equity was 10, a 2% rate move just wiped out more than the entire capital cushion on paper.
That is why the Basel Committee on Banking Supervision (BCBS) sets a supervisory "outlier" test: if a standard rate shock reduces EVE by more than 15% of Tier 1 capital (the highest quality capital, mostly common equity), the bank flags for supervisory attention. In the EU this is enforced through the European Banking Authority (EBA) guidelines; in the US, the Federal Reserve and OCC (Office of the Comptroller of the Currency) supervise IRRBB through examinations rather than a hard formulaic charge.
The BCBS standards on IRRBB lay out the six prescribed rate shock scenarios (parallel up, parallel down, steepener, flattener, and two short-rate shocks).
Ask for the bank's EVE and NII sensitivity table under standard shocks. A well-run bank shows the impact of a +200bp and -200bp shift on both measures. Red flag: large negative EVE sensitivity combined with a heavy "held to maturity" bond book and a flighty deposit base. That was the SVB signature.
Market risk is the risk of loss on trading-book positions from moves in prices, rates, FX, equities, or commodities. Unlike IRRBB, this is marked to market daily, so losses show up fast.
The classic failure mode is concentration plus weak controls. In 2008, Jerome Kerviel at Societe Generale built unauthorized positions estimated near 50 billion euros, producing a loss of about 4.9 billion euros when unwound. In 2012, JPMorgan's "London Whale" lost an estimated 6.2 billion dollars on outsized credit derivative positions that breached internal risk limits. In both cases the trades were visible in the data; the controls failed to act.
Basel measures market risk two ways:
VaR's blind spot: it says nothing about the day you breach it. A trader can sit comfortably inside VaR limits while building a position that detonates in the tail. That is exactly the Whale scenario.
Knowledge check
1. The failure of a bank with zero loan defaults but collapsing bond values best illustrates which principle?
2. Why does classifying bonds as 'held to maturity' in the banking book create a place where risk can hide?
3. A bank funds long-term fixed-rate mortgages with short-term deposits. When rates rise sharply, why does its margin get squeezed?
4. Select ALL correct answers about the distinction between EVE and NII as measures of IRRBB.
Select all the correct answers.
5. Select ALL correct answers that correctly distinguish the banking book from the trading book.
Select all the correct answers.
Operational risk is the risk of loss from failed internal processes, people, systems, or external events. Translation: fraud, cyberattacks, IT outages, mis-selling fines, and rogue trading itself.
For years this was the neglected risk. Then the losses piled up. Estimates put global conduct and litigation costs at banks in the hundreds of billions of dollars over the decade following 2008. Regulators responded.
Under Basel's Standardised Approach for Operational Risk (SA-OR), capital is driven by a Business Indicator (BI), a proxy for a bank's size and income, scaled up as the bank grows, and multiplied by an Internal Loss Multiplier that rises if the bank has a poor historical loss record. In plain terms: bigger banks and banks that lose more money to operational failures must hold more capital.
Concrete triggers you will recognize:
Pull the operational loss database. Look at frequency and severity by category over five years. A rising trend in "external fraud" or "clients, products and business practices" (the Basel loss-event category covering mis-selling and legal settlements) tells you where the next fine may land. Then check third-party concentration: if one cloud provider underpins core banking, a single outage is now a capital-relevant event.
These risks are not siloed. A rate shock (IRRBB) can force asset sales that crystallize market-risk losses, which may reveal an operational-risk control gap in how positions were valued. SVB was all three at once: interest-rate mismatch, a bond portfolio marked far below cost, and a supervisory-oversight failure. The bank held plenty of capital against credit risk. It held almost nothing against the risks that actually killed it.