Early assignment on the short leg, and dividend risk

A vertical spread's max loss is defined. Its mechanics are not. The short leg of every spread on an American-style option can be exercised against you at any time, and when that happens the spread you owned is replaced by stock plus a single option. The loss is still capped, but the buying power, the Greeks and the decisions are suddenly different. This lesson covers when it happens and what to do.

When early exercise is rational

Exercising an option early throws away whatever extrinsic value it has. So early exercise happens only when extrinsic is close to zero and there is something to gain by not waiting:

• Deep in-the-money puts. Exercising a put delivers cash (the strike) now instead of at expiration. When the interest on that cash exceeds the put's remaining extrinsic value, exercise makes sense. Practically: ITM puts with almost no extrinsic get assigned, and the deeper and closer to expiry, the more likely.
• In-the-money calls the day before an ex-dividend date. A call holder does not receive the dividend; a stock holder does. If the dividend is larger than the call's extrinsic value, the holder exercises the evening before the ex-date, and the short is assigned.

Everything else, including "the option is in the money," is not by itself a reason. Options that are in the money with meaningful extrinsic value are almost never exercised early because selling them pays more.

Example 1: the short put gets assigned

XYZ at $50, you sold the 45/40 bull put spread for $0.45. The stock falls to $41 with 8 days left. The $45 put is worth $4.05: intrinsic $4.00, extrinsic $0.05. One evening you are assigned.

The payoff has not gotten worse; long stock plus a long $40 put is a synthetic long $40 call, which is the spread's loss profile with the upside cap removed. What has changed is that you now hold $4,100 of stock in an account that may have been sized for a $455 max loss. If the account cannot carry it, the broker will liquidate, and not at a price you choose.

Your choices:

1. Sell the shares and sell the $40 put. This books the spread's loss at the current prices and returns you to cash. Usually the right answer.
2. Exercise the $40 put to sell the shares at $40. Only sensible if the stock is below $40 and the put has no extrinsic left; otherwise you are throwing away the put's time value. Selling both is almost always better.
3. Keep the synthetic call if you are bullish on XYZ. Legitimate, but be aware it is a new trade with a new buying power requirement.

Assignment can also be partial: two of five contracts assigned, three still short.

Example 2: the short call and the dividend

You sold the 55/60 bear call spread on XYZ for $0.50. XYZ has risen to $57, there are 10 days left, and tomorrow is the ex-dividend date for a $0.50 dividend. The $55 call is worth $2.15: intrinsic $2.00, extrinsic $0.15.

Extrinsic $0.15 is less than the $0.50 dividend. A rational call holder exercises tonight, gets the shares, and collects the dividend tomorrow. You are assigned: short 100 shares at $55, still long the $60 call.

The dividend is a pure extra loss on top of the spread's loss. It happens to anyone short an ITM call through an ex-date when extrinsic is smaller than the dividend, and it is entirely avoidable.

Short ITM call, day before ex-dividend

  Extrinsic value of the call  vs  dividend
  ------------------------------------------
  0.15  <  0.50    assignment very likely   -> close or roll today
  0.45  <  0.50    assignment likely        -> close or roll today
  0.80  >  0.50    assignment unlikely      -> watch, no action required

The rules

• Check ex-dividend dates before opening any spread with a short call, and again whenever the short call goes in the money.
• If a short call is ITM and its extrinsic is below the dividend, close or roll the spread before the ex-date. Rolling to a higher strike or a later expiration restores extrinsic value.
• If a short put is deep ITM with near-zero extrinsic, expect assignment, and decide in advance whether you can carry the shares. If you cannot, close the spread.
• Know your product. Cash-settled index options (SPX, XSP, NDX, RUT and similar) are European style: no early assignment, ever, and no dividends. ETF options and single-stock options are American style with dividends. Index options remove this entire lesson from your risk list, at the cost of different tax and settlement rules covered in the fundamentals course.
• Assignment notices arrive overnight. You find out the next morning. If a position could be assigned and you would not want the result, act the day before, not the day of.

Key idea: Early assignment happens when the short leg has almost no extrinsic value: deep ITM puts, and ITM calls the evening before a dividend larger than their extrinsic. It does not increase the max loss, but it replaces a small defined-risk spread with a stock position and, for short calls, adds the dividend as an extra loss. Close or roll before it happens; European-style index options make it impossible.

Try it: Find a dividend-paying stock with an ex-date in the next two weeks. Look at the ITM calls expiring after the ex-date and record each one's extrinsic value against the dividend. Mark which ones you would expect to be assigned tonight if you were short them.

Recap

• Early exercise is rational only when extrinsic ≈ 0: deep ITM puts, and ITM calls before a dividend larger than their extrinsic.
• Assignment on a short put leaves you long stock plus the long put: same max loss, unlimited upside, much more buying power.
• Assignment on a short call before an ex-date leaves you short stock and owing the dividend.
• Close or roll ITM short legs with low extrinsic before ex-dates; sell shares and the remaining leg rather than exercising after a put assignment.
• Cash-settled index options are European style with no early assignment and no dividends.