Generally speaking, an option can be assigned at any time prior to expiration, and Mike Scanlin of BornToSell.com details the most commonly asked questions about how the process works.
As the market nears closing time on expiration Friday, covered call writers want to know if they will be assigned or not for tax reasons, margin reasons, and portfolio optimization reasons. Let's look at the issue from the point of view of both people involved in the trade: the option holder who is long the call option, and the covered call writer who is short the same call option.
"Assignment" means the call option you sold short as part of your covered call trade is now being exercised. That means some option holder somewhere wants his stock and you have been chosen by the OCC (Options Clearing Corp) to receive the assignment. It's a random process; each time the OCC gets an exercise notice they randomly choose from among all the short calls (in the same series) who will receive the assignment.
If you are chosen by OCC, your broker will be notified and your broker will, in turn, notify you. You will need to make good on your promise to deliver the shares of stock and, in exchange, receive the strike-price-per-share in cash, as per the option agreement.
What Determines if the Option Holder Exercises?
It's really up to them. It's their option and they can do what they want with it. They can even exercise it if the stock price is below the strike price of the option (i.e. it's out of the money). It wouldn't make any economic sense to do so, but it is allowed. The option holder has the right to exercise at any time for any reason.
Normal Circumstances When Call Options Are Exercised by Rational People
1. The stock closes above the strike price on the option's expiration day.
This is the typical case for exercise. The option holder exercises his in-the-money option to acquire the stock for less than the current price. He only has to pay the strike price. If the stock closes at $43 and the strike price is 40, he only pays $40/share to acquire the stock.
2. For in-the-money options, the day before ex-dividend day when there is zero time premium remaining in the option.
This is called "early exercise" and normally only happens when there is no time premium left in the option because the option holder forfeits any remaining time premium when he exercises. It doesn't make economic sense for him to exercise when there is still time premium remaining in the option; he's better off just selling the option in that case. But if there is zero time premium and he knows the stock is likely to open lower the next morning by the amount of the dividend that is about to be paid, he will do an early exercise to capture the dividend.
What About the Day Before Earnings?
That's not a good time to exercise an option. There will be lots of time premium in the option (which will be forfeited if exercised) because of earnings uncertainty. If the option holder wants out of the position (maybe he's worried about volatility decreasing after earnings come out, which could lower the value of his option) then he's better off just selling the option instead of exercising it.
NEXT PAGE: Various Scenarios
What if the stock closes very near the strike price?
This one is tricky.
For starters, stocks continue to trade for several hours in the aftermarket after the regular market closes. The stock's closing price Friday at 4:00 pm Eastern Time (regular market hours closing) may not represent the closing price during extended hours trading. And option holders have until Saturday (when options technically expire) to give their brokers exercise notices. So it's possible for a stock to close just below the strike price during regular hours on expiration Friday but then close above the strike price in extended hours. In that case the option would likely be exercised. But not always.
It depends on several factors: (1) What are the transaction costs of the person doing the exercising? (2) What is the personal opinion of the option holder for the stock at Monday morning's open? It's possible the option could finish slightly in the money during extended trading hours and still not be exercised because the option holder believes the stock will open lower (below the strike price) on Monday morning. Maybe there's some event happening over the weekend that he believes will cause the stock (or the whole market) to open lower on Monday.
Imagine a covered call that has been written at a strike of 50. On expiration Friday at the close the stock's price was within a few pennies of 50 (above or below; it doesn't matter). Will it be exercised?
It depends on what the option holder believes will happen Monday morning. And not all option holders believe the same thing, causing less than 100% of all 50-strike options to be exercised. And since option assignment is random, you can't be sure if you'll be assigned or not. The purple oval here is a mystery and subject to personal opinion:
The decision to exercise (or not) is the option holder's right but not his obligation. He can let in-the-money options expire unexercised if he so chooses, based on his beliefs of where the stock will open on the next trading day.
My Stock is Within a Few Cents of the Strike Price and It's Almost Closing Time on Expiration Day. What Should I Do?
This is the most common question. The answer is "it depends," "do you feel lucky?," and "you can never tell for sure." If you don't want the stock called away for whatever reason (taxes, margin, etc.) then buy the call option back before the option market closes. It may cost you a nickel or two (plus an option trade commission) but that's the only certain way to avoid assignment.
Remember, stocks trade for a few more hours after the regular market closes so if your stock closes 10 cents below the strike during regular hours but then rises 25 cents above the strike during extended hours then you are probably out of luck. It will likely be called away (unlike stocks, options don't trade after hours, so you can't buy the option back during extended trading hours).
If you are in a situation where you don't want something called away, then the best plan is to monitor the amount of time premium remaining in the option. Most option holders won't exercise if the time premium is greater than zero. If your time premium is getting small (5 to 10 cents, depends on the bid-ask spread of the underlying stock) then it's a good time to roll the option to something that has more time premium in it. The greater the time premium the smaller chance of exercise.
How Do I Calculate Time Premium?
The short answer for in-the-money options is (strike price + call price) minus stock price. So if the stock is 53 and you've sold a 50-strike call currently trading at 4 then the time premium is (50 + 4) - 53 = 1. There is 1 point of time premium in the option.
The longer answer is that stocks and options have bid prices and ask prices. So which to use? Or should you use the last trade price? We'll cover that in a future article.
By Mike Scanlin, CEO, BornToSell.com