Assignment risk / early assignment
早期権利割当リスク。売りオプションが満期前に割り当てられる可能性で、配当前後のイン・ザ・マネーのコールで最も起こりやすい。
Assignment happens when the holder of an option exercises it and, as the option seller, you are obligated to fulfill the contract. Sell a put and get assigned, and you must buy 100 shares at the strike; sell a call and get assigned, and you must deliver 100 shares. American-style equity options can be assigned any day before expiration, which is where the word early comes in. You never control the timing; the long side decides.
In practice, early assignment on calls tends to cluster around ex-dividend dates. If you are short a call that is in the money and the extrinsic value left is smaller than the upcoming dividend, the holder has a reason to exercise early to capture that payout, leaving you short the stock and on the hook for the dividend. Deep in the money puts can also be assigned early when almost no time value remains.
A common mistake is holding a short in the money leg through ex-dividend and assuming it is safe because expiration is still weeks away. Watch the extrinsic value of your short options: when it shrinks toward zero, assignment risk climbs. Rolling or closing the position beforehand is usually cheaper than being caught with an unwanted stock position and a margin call the next morning.
すべてのオプション用語
教育目的のみ。気配値は約15分遅延しており、本サイトの内容は投資助言ではありません。オプション取引には多大な損失リスクが伴います。