# SPAN Margin: Scenario Scanning, Offsets, and Sudden Increases

Understand how CME SPAN uses risk arrays and portfolio charges, why requirements can jump, and why SPAN is not the universal margin formula for U.S. equity options.

Canonical: https://wiki.fcontext.com/options/span-margin/
Fact checked: 2026-07-22

> For educational purposes only; not investment advice.

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## Direct answer

**SPAN**, or Standard Portfolio Analysis of Risk, is CME's scenario-based methodology for estimating a portfolio's performance-bond requirement. A risk array records how each contract is expected to gain or lose under combinations of underlying-price change, volatility change, and time passage. Positions on a common underlying are combined, recognized spread credits and other charges are applied, and the resulting requirement is subject to a short-option minimum.

SPAN is especially associated with futures and options on futures. It is **not** the universal customer-margin formula for listed U.S. stock and equity-index options. Those securities accounts may use strategy-based margin or FINRA Rule 4210 portfolio margin, brokers can impose higher house requirements, and OCC uses STANS for clearing-member portfolios. Always identify the product, account type, clearing venue, broker methodology, and current parameter file before calling a number “SPAN margin.”

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## How scenario scanning becomes a requirement

CME describes classic SPAN as evaluating risk scenarios defined by the exchange or clearing organization. The scenarios revalue contracts across price and volatility moves, with time to expiration reduced. The largest relevant scenario loss for a combined commodity is its **scan risk**.

A simplified conceptual calculation is:

`SPAN risk requirement = scan risk + intra-commodity spread charge + delivery risk − inter-commodity spread credit`

The result is then compared with the **short-option minimum**, and the larger value applies. Requirements across combined commodities are converted to a common currency and summed. This expression explains the architecture; it is not enough to reconstruct a live clearing or broker calculation.

Key inputs can change independently:

- **Price scan range:** the assumed underlying move used to form scenarios.
- **Volatility scan range:** the assumed option-volatility move.
- **Risk array:** contract-level scenario profit and loss generated from current inputs.
- **Spread parameters:** rules for recognizing or charging relationships within and across combined commodities.
- **Delivery risk:** extra risk as physically delivered products approach delivery.
- **Short-option minimum:** a floor for residual risk in portfolios with deep out-of-the-money short options.

An exchange or clearing organization publishes parameter files at least once each business day, according to CME's overview. A clearing firm or broker may update requirements intraday, add house buffers, restrict offsets, or demand more collateral. Margin is collateral against modeled exposure, not a down payment and not a maximum-loss estimate.

### Why the requirement can rise without a new trade

The portfolio changes as prices, volatility, and time change. Separately, the risk authority can widen scan ranges, reduce credits, increase delivery charges, or raise a minimum. A hedge can also stop offsetting because its Delta changed, it moved to another expiry bucket, became illiquid, or expired. These effects can coincide during stress, when available cash is most valuable.

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## Example: a parameter and offset shock

Assume a clearing report for one combined commodity shows these **illustrative outputs**:

| Component | Initial report | Stressed report |
| --- | ---: | ---: |
| Scan risk | `$12,000` | `$16,000` |
| Intra-commodity spread charge | `$1,500` | `$2,000` |
| Delivery risk | `$500` | `$1,000` |
| Inter-commodity spread credit | `−$3,000` | `−$2,000` |
| Calculated requirement | `$11,000` | `$17,000` |
| Short-option minimum | `$4,000` | `$5,000` |

Initially:

`$12,000 + $1,500 + $500 − $3,000 = $11,000`

Because `$11,000` exceeds the `$4,000` short-option minimum, the requirement is `$11,000`. After volatility and delivery stress increase while the recognized credit falls:

`$16,000 + $2,000 + $1,000 − $2,000 = $17,000`

The requirement rises by `$6,000`, or about `54.5%`, despite unchanged contract counts. If the account had only `$3,000` of excess liquidity, it now has a simplified `$3,000` deficit. A firm can demand funds or liquidate under its agreement; the example does not imply a guaranteed notice period.

The figures are designed to teach the components. Real risk arrays, extreme scenarios, offsets, currency conversion, variation flows, concentration measures, and house add-ons must come from the applicable files and firm statement.

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## Controls before relying on displayed margin

- Confirm whether positions are futures, options on futures, equity options, index options, or security futures; the governing margin framework differs.
- Reconcile quantity, contract multiplier, underlying, expiry, deliverable, currency, and account allocation.
- Obtain the dated parameter file and identify the exchange, clearing organization, and software version.
- Compare requirement after removing each major spread credit rather than assuming the hedge is permanent.
- Stress wider price and volatility ranges, gap moves, correlation breaks, and unavailable quotes together.
- Treat deep out-of-the-money short options as tail liabilities even when their current Delta and premium are small.
- Track delivery periods, settlement method, exercise, assignment, and physical funding obligations.
- Keep liquidity beyond the displayed excess; margin and market loss can increase simultaneously.
- Read the broker's house-margin, concentration, liquidation, and intraday-call terms.
- Do not infer maximum loss, probability of loss, or trade quality from a lower requirement.
- For U.S. securities options, compare the actual account treatment with FINRA Rule 4210 and the broker disclosure rather than relabeling it SPAN.
- Recheck current rules and parameter files; numeric requirements are time-sensitive.

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## Common misconceptions

- **“SPAN is one fixed percentage.”** It is a portfolio scenario framework whose inputs and credits vary.
- **“The worst scenario is the maximum possible loss.”** Scan ranges target modeled coverage; markets can move farther and liquidity can disappear.
- **“A spread always receives full credit.”** Only recognized offsets qualify, and parameters or position changes can reduce them.
- **“No trade means no margin change.”** market moves, time, volatility, parameter updates, delivery proximity, and house rules can all change it.
- **“Every U.S. option account uses SPAN.”** Equity-options customer margin, OCC clearing margin, and futures margin are distinct layers and may use different methods.
- **“More collateral closes the risk.”** Collateral protects against default exposure; it does not hedge price, volatility, assignment, or liquidity risk.

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## Related topics

- [Option margin](/options/option-margin/)
- [Portfolio margin for options](/options/portfolio-margin-options/)
- [Option stress testing](/options/option-stress-testing/)
- [Options Clearing Corporation](/options/options-clearing-corporation/)

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## Authoritative sources

- [CME Group: SPAN Methodology Overview](https://www.cmegroup.com/solutions/risk-management/performance-bonds-margins/span-methodology-overview.html)
- [CME Group: SPAN Reference Documents](https://www.cmegroup.com/solutions/risk-management/performance-bonds-margins/span-reference-documents.html)
- [CFTC: Futures Glossary](https://www.cftc.gov/LearnAndProtect/AdvisoriesAndArticles/CFTCGlossary/index.htm)
- [FINRA Rule 4210: Margin Requirements](https://www.finra.org/rules-guidance/rulebooks/finra-rules/4210)
- [OCC: Margin Methodology](https://www.theocc.com/risk-management/margin-methodology)