Rights and obligations
A call gives its buyer the right to buy 100 shares at the strike price until expiration; a put gives the right to sell at the strike. The buyer pays the premium and can walk away, so the most a buyer can lose is the premium. The writer (seller) keeps the premium and must deliver (call) or buy (put) if the option is exercised, so the most a writer can gain is the premium.
At expiration
call worth = max(0, stock − strike)
put worth = max(0, strike − stock)
Subtract the premium for a buyer, or add it for a writer, and you have the profit. That gives the breakevens:
call: strike + premium put: strike − premium
The four corners and two combinations
- Long call: gain unlimited, loss = premium.
- Short (naked) call: gain = premium, loss unlimited: the stock has no ceiling.
- Long put: gain = strike − premium (the stock can only fall to zero), loss = premium.
- Short put: gain = premium, loss = strike − premium.
- Covered call (own the shares, write a call): breakeven = cost − premium; gain capped at strike − cost + premium; loss = cost − premium if the stock goes to zero. Income for a holder willing to sell at the strike.
- Protective put (own the shares, buy a put): breakeven = cost + premium; gain unlimited; loss limited to cost − strike + premium. Insurance.
Intrinsic value and time value
Before expiration, the premium has two parts:
premium = intrinsic value + time value
Intrinsic value is what exercising right now would be worth: stock minus strike for a call, strike minus stock for a put, never below zero. An option with intrinsic value is in the money; at the strike it is at the money; otherwise it is out of the money. Whatever is left of the premium is time value, the price of the chance that the stock moves before expiration. It melts to zero on expiration day.
In the money is not the same as profitable. A buyer who paid $3.50 for a 45 call is in the money at $47 but still needs $48.50 to break even.
Check yourself
- A 40 call trades at $5.25 with the stock at $43. Find the intrinsic value, time value and breakeven.
Answer
Intrinsic $43 − $40 = $3.00; time value $5.25 − $3.00 = $2.25; breakeven $40 + $5.25 = $45.25.
- An investor buys an ABC 60 put for $4. Find the maximum loss, maximum gain and breakeven for one contract.
Answer
Loss: the $400 premium. Gain: ($60 − $4) × 100 = $5,600 if ABC goes to zero (not unlimited). Breakeven $56.
- An investor writes a 35 put for $2. What are his maximum gain and loss per contract?
Answer
Gain: the $200 premium. Loss: ($35 − $2) × 100 = $3,300, if he must buy at $35 a stock that has fallen to zero.
- She bought 100 shares at $62 and a 60 put for $1.50. What is her worst case, and her result if the stock rises to $75?
Answer
Worst case: sell at $60 through the put, losing $2 on the shares plus the $1.50 premium: $350, however far the stock falls. At $75: $13 − $1.50 = $11.50 a share, $1,150.
A bit of history: Aristotle tells how Thales of Miletus paid small deposits in winter for the use of every olive press at harvest, and profited when a great crop came: the right without the duty, the oldest option on record.
“A prudent man foreseeth the evil, and hideth himself; but the simple pass on, and are punished.” — Proverbs 22:3