Assignment Risk Calculator
Enter a short option to see its probability of finishing in the money, whether an upcoming dividend makes early assignment likely, and whether it sits in the pin-risk zone.
Per share. Option price minus intrinsic value — use the bid, since that is what the holder gives up.
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American-style equity and ETF options only. Cash-settled European index options (SPX, NDX, RUT) cannot be exercised early, so the early-assignment tests above do not apply to them.
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How to Use the Assignment Risk Calculator
Describe the short option
Stock price, strike, call or put, and days to expiration. The calculator assumes you are short the contract, so assignment is the outcome being measured.
Add implied volatility and the rate
Both feed d2. Use the option's own IV rather than a broad index number — a skewed strike can differ by ten volatility points or more, which moves the probability materially.
Enter the extrinsic value
Take the option's price and subtract its intrinsic value. This single number decides early assignment: it is what the holder forfeits by exercising ahead of expiration.
Fill in the dividend for short calls
Enter the dividend per share and the ex-dividend date. If the ex-date falls before expiration, the calculator runs the dividend against the remaining extrinsic value and flags the result.
What each output means
- % Prob. finishing ITM: N(d2) for a call, N(-d2) for a put — the risk-neutral chance the option is in the money at expiration, and therefore auto-exercised.
- Δ Delta: shown for comparison only. Traders use it as a quick stand-in for assignment odds, but it is N(d1), a different quantity.
- $ Moneyness: how far in or out of the money the strike sits, in dollars and percent.
- ! Early assignment test: dividend versus extrinsic value for short calls, interest carry versus extrinsic value for short puts.
- = OCC auto-exercise: whether the option would be exercised automatically if expiration happened at the current price.
- ~ Pin risk: whether the stock is sitting close enough to the strike, close enough to expiration, for the outcome to be genuinely uncertain.
The Dividend vs Extrinsic Value Test for Short Calls
Early exercise of an American call is normally irrational: exercising converts the option into stock and throws away whatever extrinsic value is left. A dividend is the exception. Only shareholders of record receive it, and an option holder is not a shareholder, so on the day before the ex-dividend date the holder of an in-the-money call faces a straight trade — exercise, forfeit the remaining extrinsic value, and collect the dividend instead.
That makes the test arithmetic rather than opinion. If the dividend exceeds the call's remaining extrinsic value, exercising early is worth more than holding, and the short call should be treated as likely to be assigned. While extrinsic value stays above the dividend, exercising destroys value and early assignment stays rare. Deep in-the-money calls are the ones at risk because they are the ones with almost no extrinsic value left. Our full guide to early assignment risk covers the allocation process and how to close or roll ahead of the ex-date.
Worked example
Stock: $52.00, ex-dividend in 3 days for $0.30
Position: short 1 $50 call, 10 days to expiration
Intrinsic value: $2.00 ($52.00 − $50.00)
Call bid: $2.18, so extrinsic value = $0.18
Test: $0.30 dividend > $0.18 extrinsic
Result: exercising early nets the holder $0.12 per share — assignment likely
The same position with $0.45 of extrinsic value fails the test and is unlikely to be assigned early, because the holder would give up $0.45 to collect $0.30. Two practical notes: use the bid for extrinsic value, since that is what the holder could actually sell for, and re-run the test each day into the ex-date — extrinsic value decays while the dividend does not.
Short Puts, Auto-Exercise and Pin Risk
Short puts: interest, not dividends
A put holder who exercises receives the strike in cash immediately and can earn interest on it for the remaining life of the option. That carry is what makes early exercise worthwhile, so the test mirrors the call version: interest on the strike over the remaining days versus the put's leftover extrinsic value. In practice this only bites on deep in-the-money puts whose extrinsic value has collapsed toward zero, and it becomes more common as interest rates rise.
The $0.01 auto-exercise rule
The Options Clearing Corporation automatically exercises any option that is $0.01 or more in the money at the official expiration close. There is no minimum-profit test and the holder does not need to do anything. This is the single most commonly missed rule in options: a short call that finishes one cent in the money still delivers 100 shares per contract, and a short put that finishes one cent in the money still buys them.
Pin risk near the strike
When the stock sits within roughly 1% of your strike into expiration, the outcome is genuinely uncertain. Post-close movement can push the option through the auto-exercise threshold, holders can exercise or file do-not-exercise instructions, and you may be assigned on some contracts but not others. You will not know your share position until the next trading day — see pin risk for the full mechanics.
Assignment Risk Formulas
| Metric | Formula | Example |
|---|---|---|
| d2 | (ln(S/K) + (r − σ²/2)T) / (σ√T) | S $100, K $105, 30 DTE, 30% IV, r 4.5% → d2 = −0.567 |
| Prob. call finishes ITM | N(d2) | N(−0.567) = 28.5% |
| Prob. put finishes ITM | N(−d2) | 1 − 28.5% = 71.5% for the same strike |
| Delta (comparison only) | N(d1), d1 = d2 + σ√T | N(−0.481) = 0.315 — above the 28.5% N(d2) |
| Extrinsic value | Option price − intrinsic value | $2.18 − $2.00 = $0.18 |
| Short call early-exercise test | Dividend > extrinsic value | $0.30 > $0.18 → assignment likely |
| Short put early-exercise test | K x (e^(rT) − 1) > extrinsic value | $100 strike, 30 days, 4.5% → $0.37 of carry |
| Pin zone | |S − K| / K ≤ 1% near expiration | $50 strike, stock $49.60–$50.50 → pin zone |
N(d2) is a risk-neutral probability under a lognormal model, not a forecast. It ignores dividends, skew and jump risk, so treat it as a calibrated estimate rather than a guarantee.
Frequently Asked Questions
How do you calculate the probability of assignment?
Use N(d2), where d2 = (ln(S/K) + (r − σ²/2)T) / (σ√T), reading N(d2) for a call and N(−d2) for a put. A $105 call on a $100 stock, 30 days out at 30% IV with rates at 4.5%, gives d2 = −0.567 and a 28.5% chance of finishing in the money. Delta on the same option is 0.315 — close, which is why it gets used as shorthand, but it answers a different question.
When does a short call get assigned early?
Almost always the day before an ex-dividend date, on an in-the-money call whose remaining extrinsic value is smaller than the dividend. The holder exercises, gives up the leftover time value, and takes the dividend instead. If the dividend is $0.30 and the call has $0.18 of extrinsic value, exercising is worth $0.12 per share and assignment should be expected. While extrinsic value exceeds the dividend, early exercise destroys value and is rare.
Is an option that expires one cent in the money exercised?
Yes. The OCC automatically exercises any option that is $0.01 or more in the money at the official expiration close, with no minimum-profit test and no action required from the holder. A short call one cent in the money delivers 100 shares per contract; a short put one cent in the money buys 100. Holders can submit a do-not-exercise instruction, but most retail brokers do not expose that control.
Can a short put be assigned early?
Yes, driven by interest rather than dividends. Exercising hands the put holder the strike in cash today, which can then earn interest for the remaining life of the option. Compare that carry against the put's remaining extrinsic value: when carry is larger — typically on deep in-the-money puts with extrinsic value near zero — early exercise is rational, and it becomes more common as rates rise.
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