Why Securities Can Create Market Risk Inside a Bank

The first risk is interest rates

When market interest rates rise, the price of an existing fixed-rate bond usually falls because new investors can obtain higher yields elsewhere. When rates fall, the bond’s price usually rises.

market yield rises → fixed cash flows are discounted more heavily → present value falls.

The longer the duration, the larger the price sensitivity tends to be for a given move in yields.

This connects directly to Interest-Rate Risk in the Banking Book.

Credit spread risk is different from default risk

A corporate bond can continue paying on time while investors demand a higher yield because they perceive more credit risk, liquidity risk or uncertainty. The bond’s price falls even though no default has occurred.

The widening spread is a market repricing of risk.

This is why a bank can experience a market-value loss before accounting credit impairment reaches the same conclusion.

Equity securities create direct price risk

If a bank owns shares, the value can move with corporate earnings, industry prospects, market sentiment, interest rates and broader risk appetite. Unlike a loan, an equity claim has no contractual principal repayment date that anchors value in the same way.

Equity exposure can therefore move quickly and non-linearly, especially during market stress.

Foreign securities add currency risk to price risk

A US-dollar bond can rise in dollar terms while the US dollar falls against the bank’s reporting currency. The bank’s final return then depends on both the bond and the currency.

The bank can hedge the FX component separately, but the hedge introduces its own counterparty, basis and liquidity mechanics.

Read How Foreign-Exchange Risk Enters a Bank.

Market liquidity changes how much the quoted price is worth in practice

A bank can see a market price on a screen and still be unable to sell a large position near that price. During stress, bid-ask spreads widen, dealers reduce balance-sheet capacity and buyers disappear.

The relevant risk is therefore not only mark-to-market movement but mark-to-exit: what price can the bank actually obtain when it needs liquidity?

This connects securities market risk to High-Quality Liquid Assets.

The trading book and banking book treat securities differently

The Basel Framework maintains a regulatory boundary between positions held for trading purposes and positions held in the banking book. Trading-book positions are subject to the market-risk capital framework. Banking-book securities can instead be affected through interest-rate risk, credit-spread risk, credit risk and accounting valuation depending on the instrument and classification.

The same bond therefore can create different regulatory treatment depending on why and how the bank holds it.

Accounting classification changes where price movement appears

Some securities are measured through profit and loss, some through other comprehensive income, and some can be held at amortised cost if the applicable accounting criteria are satisfied.

Those classifications affect when market movements enter reported earnings or equity. They do not make the economic sensitivity disappear.

accounting location of the loss ≠ absence of economic loss.

A bond held to maturity can still create risk before maturity

If the bank truly holds a sound bond until maturity, interim market-price movement may not determine the final contractual cash flow. But the bank can still suffer in several ways:

• the bond can lose economic value;
• funding cost can rise above its fixed yield;
• the bank may need to sell it for liquidity;
• collateral haircuts can rise;
• credit spreads can signal deterioration;
• capital or accounting effects can appear depending on classification.

“We plan to hold it” reduces one path to realised loss. It does not erase every risk path.

A forced sale changes unrealised loss into realised loss

A bank can carry a security whose market value has fallen while expecting to recover more over time. If deposit outflows force the bank to sell immediately, the market discount becomes a realised loss.

rate shock → security price falls → deposit outflow → forced sale → realised loss → capital weakens.

This is one of the most important bridges between market risk and liquidity risk.

Collateral value can fall even while the security remains eligible

A bank can pledge securities for secured funding. If market value falls, lenders or central-bank frameworks can apply larger haircuts or require additional collateral.

The bank therefore receives less cash from the same nominal face amount.

Read Secured Bank Funding.

Duration concentrates sensitivity into time

A short Treasury bill and a thirty-year bond can have the same face value but very different sensitivity to interest-rate changes. Longer cash-flow horizons generally create greater duration.

A securities portfolio therefore needs to be understood by tenor and duration, not simply total market value.

Convexity matters when rate moves become large

Duration is a useful first approximation, but the relationship between bond price and yield is curved. Large rate movements therefore produce price changes that are not perfectly captured by a linear duration estimate.

Convexity and embedded options make the sensitivity more complex, especially for mortgage-related or callable securities.

Embedded options can make securities behave differently when rates move

A callable bond can be redeemed by the issuer when rates fall, limiting the investor’s upside. Mortgage-backed securities can receive faster principal repayment when borrowers refinance.

The bank therefore cannot assume that contractual maturity is the same as economic duration.

Credit spread widening can create a liquidity spiral

If spreads widen, bond prices fall. Falling prices reduce collateral value. Lower collateral value can trigger margin calls or reduce secured funding capacity. The bank then needs more liquidity, potentially forcing more asset sales.

The market-risk shock has become a funding shock.

A worked miniature

A bank holds S$500 million of long fixed-rate securities. Market yields rise enough that the portfolio’s market value falls by 8 per cent.

The mark-to-market decline is S$40 million. If the bank can hold the securities and they ultimately repay as expected, part of the market-value loss can reverse over time. If the bank must sell S$200 million of the portfolio during stress at the lower price, the relevant portion of the loss becomes realised.

The same rate shock therefore has a different outcome depending on funding and liquidity.

Hedging securities risk creates offsetting sensitivities

Banks can use futures, swaps, options, credit derivatives and portfolio structure to reduce market risk. A bond-duration exposure can be offset with interest-rate derivatives. Foreign-currency exposure can be hedged separately.

The hedge must match the risk factor closely enough. If it tracks a different rate, spread or maturity, basis risk remains.

Article 52 owns that residual mismatch.

Diversification helps only when risk factors are genuinely different

A portfolio of one hundred bonds can still be concentrated if every issuer depends on the same property market or every security has similar duration.

Market diversification therefore asks what common shock moves the positions together, not how many line items exist.

Market-risk limits turn sensitivity into governance

Banks can control positions using measures such as sensitivities, stress loss, concentration, tenor limits and value-at-risk or expected-shortfall frameworks where applicable.

The measurement architecture can differ by desk and regulatory approach. The governance principle does not: the bank should know how much it can lose before the market moves, not after.

Stress testing should combine market moves rather than isolate one price

A realistic severe scenario can combine higher rates, wider credit spreads, weaker equities, adverse FX and thinner market liquidity. Correlations often rise during stress.

The bank therefore should not assume every hedge and diversification benefit remains as effective as it was in calm markets.

Read Bank Stress Tests.

Market risk can damage capital without a credit default

If fair-value losses flow through earnings or equity, the bank’s capital base can weaken. If losses are realised through forced sales, retained earnings fall. If the securities are used as collateral, lower values can consume liquidity.

A security therefore can be “money-good” at maturity and still create serious banking stress on the path to maturity.

Four misconceptions to remove

Misconception	Better model
“A bond is safe if the issuer does not default.”	Rates, spreads and liquidity can still move the bond’s value materially.
“Holding a security at amortised cost removes market risk.”	Accounting treatment can change reported timing; economic value and forced-sale risk remain.
“An unrealised loss cannot hurt a bank.”	It can reduce collateral value, confidence and flexibility, and can become realised if liquidity forces a sale.
“More securities always improve liquidity.”	Only securities that remain monetisable at tolerable discounts provide reliable stress liquidity.

A mastery test

1. How can a security lose value without default?
2. Why is credit-spread risk different from default risk?
3. How can a market-value loss become a liquidity problem?
4. Why does accounting classification not remove economic risk?
5. How can hedging a security still leave basis risk?

If those answers connect, securities stop looking like passive assets on a balance sheet. They become moving prices connected to rates, spreads, currencies, collateral, liquidity and capital—all before the final maturity date arrives.

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