Early Exercise Assignment Risk Management

When to Use

Use this skill when a book carries short American-style option positions — covered call income programs, cash-secured puts, credit spreads, or any multi-leg structure with a short leg that can be assigned before expiration. Two economically distinct drivers put a writer at risk:

Ex-dividend capture on short calls. A long call holder who exercises on the last cum-dividend session captures the dividend. Since the US move to T+1 settlement on 28 May 2024 the ex-dividend date and the record date are the same day, so an exercise on the session before the ex-date settles on the record date and makes the exerciser a holder of record. The assigned writer is short the stock over the ex-date and owes the dividend.
Carry-driven exercise on deep ITM short puts. Exercising a put frees the strike as cash, which then earns interest for the option's remaining life. The higher the rate and the longer the remaining life, the sooner a put's extrinsic value collapses to the exercise boundary.

When NOT to Use

European-style options. SPX, NDX, XEO and similar cannot be exercised before expiration; the engine short-circuits them to LOW_RISK. Their expiry-day exposure is pin risk, a different problem — see options-pin-risk-management-at-expiry.
As a settlement-method classifier. Exercise style and settlement method are independent. OEX (S&P 100) is American-style and cash-settled; XEO on the same index is European-style. Do not infer one from the other — see physical-vs-cash-settlement-handling.
As a probability model. The engine emits an ordinal assignment_risk_score (0–100), not a probability. Whether your account is assigned depends on OCC allocation to your clearing member and then the member's own FIFO / random / equally-random allocation method (FINRA Rule 2360(b)(23)(C)) applied across the open interest — none of which is an input here.
As an execution or cutoff scheduler. The engine takes day counts you supply. It does not know your broker's early-exercise cutoff, holiday calendar, or session clock.
On long positions. This is a writer's screen. For the holder-side exercise-vs-sell decision use american-vs-european-style-option-exercise-handling.

Prerequisites

Short position details: position_id, symbol, option_type (CALL/PUT), exercise_style (AMERICAN/EUROPEAN), strike, option_market_price, underlying_price, contracts_qty (positive count), days_to_expiry, contract_multiplier (100 for standard US equity options).
option_market_price should be the bid, not the mid or last. A rational holder exercises only when exercising beats selling, and selling realises the bid. Feeding the mid overstates extrinsic value and therefore understates assignment risk.
Declared dividend details where applicable: upcoming_dividend_usd (per share) and days_to_ex_div. Leave days_to_ex_div at its +inf default when no dividend is scheduled.
Optional but strongly recommended: same_strike_put_price (same strike, same expiry) and an engine risk_free_rate. Supplying them upgrades the call test from a conservative screen to the exact condition.

Workflow

Intrinsic & Extrinsic Decomposition:
- $\text{Intrinsic}{\text{call}} = \max(0, S - K)$, $\text{Intrinsic}{\text{put}} = \max(0, K - S)$; $\text{Extrinsic} = \max(0,\ P - \text{Intrinsic})$.
- Decision point: if $P < \text{Intrinsic}$ the quote is below parity. The reported extrinsic is clamped at zero, but the condition is preserved as quoted_below_parity and a QUOTE_BELOW_INTRINSIC data-quality flag — exercising already beats selling, and the mark may equally be stale or crossed. Verify the quote before acting on it.
Exercise-Style Gate: European-style positions return LOW_RISK immediately. An unrecognised option_type or exercise_style is rejected, never defaulted — a typo must not silently reclassify a call as a put or an American contract as European.
Ex-Dividend Test (short calls only):
- First check relevance: a dividend whose ex-date falls after this option expires cannot be captured by exercising it. Such a dividend is ignored and flagged DIVIDEND_AFTER_EXPIRY_IGNORED.
- Exact test when same_strike_put_price is supplied — exercise immediately before the ex-date is optimal exactly when $$D > \text{TV}{ex} = p{ex} + K\left(1 - e^{-r\tau}\right)$$ where $\text{TV}{ex}$ is the call's time value at the ex-dividend underlying price and $p{ex}$ is the same-strike, same-expiry put (Merton 1973).
- Fallback screen when it is not: $D > \text{Extrinsic}{\text{cum-div}}$. This is deliberately conservative, not exact — by put-call parity $\text{Extrinsic}{\text{cum-div}} = \text{TV}{ex} - PV(D)$, so the screen fires whenever $\text{TV}{ex} < D + PV(D)$, a strict superset of the exact condition. It over-flags and does not under-flag, which is the correct direction for a writer, but it is not evidence that exercise is certain. The report records which test ran in exercise_test_used.
- Windowing: test satisfied and $\text{DaysToExDiv} \le 1.0 \implies$ CRITICAL_ASSIGNMENT_RISK + CLOSE_OR_ROLL_SHORT_CALL. Test satisfied inside the wider 3.0-day pre-warning window $\implies$ ELEVATED_ASSIGNMENT_RISK + MONITOR.
At-Parity Test (calls and puts):
- ITM and $\text{Extrinsic} \le \max($0.05,\ 0.0005 \times K) \implies$ HIGH_ASSIGNMENT_RISK + CLOSE_OR_ROLL_SHORT_{CALL,PUT}. The relative term matters: a flat $0.05 floor is a meaningful test on a $100 strike and a meaningless one on a $5,000 strike.
- This rule is dividend-independent, so it catches carry-driven put exercise, hard-to-borrow call exercise, and any short pinned at parity — cases the ex-dividend rule alone never sees.
Severity Resolution: the reported risk_level is the most severe rule that fired, and every firing rule contributes its own sentence to risk_summary. A critical ex-dividend verdict keeps the call close/roll directive even when the parity rule also fires.
Audit Report Generation: output the structured EarlyExerciseAuditReport, carrying assignment_risk_score, exercise_test_used, early_exercise_edge_usd, assigned_share_notional_usd, dividend_liability_usd, quoted_below_parity, and data_quality_flags.

Full procedure: see references/workflows.md. Standards reference: see references/standards.md. Printable pre-flight checklist: see assets/checklist.md.

Common Pitfalls

Reading the risk score as a probability of assignment. Assignment reaches an individual account only through OCC allocation to the clearing member and then the member's FIFO / random / equally-random allocation across its short open interest (FINRA Rule 2360(b)(23)(C); Regulatory Notice 11-35). Rational exercise by holders is necessary for assignment, not sufficient for your assignment — and a low probability of being picked is no comfort when the loss is a dividend liability plus an unhedged short stock position.
Comparing the dividend to the mid. Extrinsic computed from the mid can double the apparent buffer on a wide market. The holder's alternative to exercising is selling at the bid; screen on the bid.
Comparing the dividend to the wrong time value. The desk rule "dividend > time value" and the exact rule "dividend > put + interest on strike" are not the same test. The former is a conservative screen on the cum-dividend extrinsic; treat a hit as a reason to look, not as proof exercise is optimal.
Counting a dividend the option will never see. An ex-date after expiration carries no assignment risk for that contract. Screening on the dividend alone flags 0DTE and short-dated positions that cannot be exercised into the record date.
Watching only the ex-dividend window on calls. A call pinned at parity — hard-to-borrow name, deep ITM, no dividend anywhere near — is exercisable on any session. The original version of this engine only looked at calls inside a one-day ex-dividend window and scored these LOW_RISK.
Applying an absolute extrinsic floor across all strikes. $0.05 of extrinsic on a $5,000-strike index option is not a comparable condition to $0.05 on a $100 strike.
Expecting a dividend to raise short put risk. A dividend before expiry makes put early exercise less attractive, not more — the put holder who exercises gives up the stock and the dividend with it. The engine subtracts it in the put carry edge.
Conflating American with European, or exercise style with settlement. European-style index options cannot be assigned early; American cash-settled index options (OEX) can. Neither fact follows from the other.
Acting after the cutoff. FINRA Rule 2360(b)(23)(A) fixes 5:30 p.m. ET on expiration day as the final decision deadline for expiring options, and members may set earlier deadlines. For early exercise on an ordinary session the deadline is your clearing member's own cutoff. Closing or rolling "before the ex-date" means before that cutoff on the last cum-dividend session, not the next morning.

Verification

Instantiate EarlyExerciseRiskEngine(). Submit a short American call (Strike $100, Underlying $105, Bid $5.20 → Intrinsic $5.00, Extrinsic $0.20, 10 contracts) with a $1.00 dividend 0.5 days out. Confirm risk_level == "CRITICAL_ASSIGNMENT_RISK", recommended_action == "CLOSE_OR_ROLL_SHORT_CALL", exercise_test_used == "EXTRINSIC_SCREEN", and dividend_liability_usd == 1000.0.
Re-submit the same position with same_strike_put_price=0.60, upcoming_dividend_usd=0.75 on an engine with risk_free_rate=0.05. The exact test gives $\text{TV}_{ex} = 0.60 + 100(1 - e^{-0.05 \times 15/365}) = $0.8053 > $0.75$, so the verdict is LOW_RISK — a position the conservative screen would have flagged.
Confirm a deep ITM short call at parity with no dividend anywhere (Strike $100, Underlying $140, Bid $40.01) still returns HIGH_ASSIGNMENT_RISK.
Run python -m unittest discover -s skills/early-exercise-assignment-risk-management/scripts.

Early Exercise Assignment Risk Management

When to Use

When NOT to Use

Prerequisites

Workflow

Common Pitfalls

Verification

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Handed off from 7

When to Use

When NOT to Use

Prerequisites

Workflow

Common Pitfalls

Verification

Related Skills

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Handed off from 7