Market risk is the possibility of losing value because market prices, rates or other market inputs move adversely for a position. A fully paid equity holding can suffer a market loss even when no borrower defaults and no payment is due. The practical question is: which market moves change this portfolio's value, and by how much?
The Basel Committee's definition centres on losses from movements in market prices. For a quant, the work starts by connecting positions to their risk factors, then translating changes in those factors into gains and losses.
A price move becomes a dollar loss
Consider an unlevered equity position worth USD 1,000,000 at the beginning of one holding period. Keep the shares unchanged and stipulate a 2% price decline over that period. Ignore dividends, fees, taxes and financing cash flows. These are synthetic assumptions, not observed prices or a market forecast.
The ending marked value is
Profit and loss, or P&L, is the change in value: USD. Under the convention that losses are positive,
Original synthetic one-period scenario, in USD. The unlevered shareholding is unchanged; dividends, costs, taxes and financing cash flows are excluded. No probability is assigned to the price move.
This is a mark loss: the position has fallen in market value. Selling is not required for the decline in value to exist. Sale proceeds could differ from the mark because execution has its own market liquidity risk.
The 2% is the stipulated return, not the probability of losing money. The USD 20,000 answers what happens in this scenario. It says neither how likely the scenario is nor how much capital an institution must hold. A different adverse move could produce a larger loss.
The exposure determines what counts as adverse
A falling share price hurts a long shareholding. The same direction does not hurt every position: a short position may benefit, and an option can respond nonlinearly. “The market moved down” is therefore incomplete without the holdings and the valuation rule.
| Position or valuation | Market input that can change its value |
|---|---|
| Equity holding | The particular share price, including company-specific moves |
| Fixed-rate bond | Yield-curve points and the issuer's credit spread |
| Foreign-currency asset measured in home currency | The asset's local price and the exchange rate: foreign exchange risk |
| Commodity position | The relevant commodity price or futures curve |
| Option | Underlying price, implied volatility, rates and time remaining |
Market risk is broader than systematic risk. A price loss driven by one company's news is still market risk for its shareholder, even if the rest of the market is unchanged. Systematic risk concerns the common component that diversification cannot remove.
For a complex book, the useful chain is holdings → market inputs → revaluation → P&L. A sensitivity is a local approximation to that chain; it can miss curvature when shocks are large. The Risk Factor Mapping and the Market Risk Loss Operator lesson, with a public preview and membership required for the full lesson, develops the mapping and its delta and delta–gamma approximations.
Separate the mechanism from the label
A missed promised payment is a credit-risk channel. A cash shortfall at a deadline is funding liquidity risk. A failed order-entry process is an operational-risk channel. They answer different questions from the price-revaluation calculation above.
These channels can interact. Deteriorating borrower creditworthiness can widen a bond's spread and lower its market price before any payment is missed. A process error can create an unwanted position that then loses value as prices move. The categories help identify causes and controls; they do not make the economic losses independent.
Managing market risk starts with accurate positions, relevant factors and consistent valuations. Stress testing asks what specified adverse moves would do. Value at Risk and Expected Shortfall additionally summarise an assumed or estimated loss distribution and need a stated horizon and confidence level. None turns the single scenario above into a probability estimate.
Reducing a position or hedging a factor can reduce exposure, but the hedge may leave basis risk, other factors or new cash demands. A market-risk assessment should explain those remaining exposures alongside its headline number.
Sources
- Alexander J. McNeil, Rüdiger Frey and Paul Embrechts, Quantitative Risk Management: Concepts, Techniques and Tools, revised edition, Princeton University Press, 2015, §1.1.2, pp. 5–6, and §9.1.1–9.1.2, pp. 326–329: financial-risk types, their interactions, fixed-position P&L, factor mapping and local approximations. The equity scenario and figure here are original and synthetic.
- Basel Committee: MAR11, Definitions and application of market risk, §11.1: price-movement definition. Its bank capital framework has a specified scope; the example above does not calculate a regulatory capital charge.
- Federal Reserve: 12 CFR §217.202, Definitions: distinguishes general market movements from position-specific risk factors within the US bank market-risk rule.