Call Option vs. Put Option: Key Differences and When to Sell

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A call option gives its buyer the right to buy an asset at a set price (the strike) before or at expiration. A put option gives its buyer the right to sell an asset at the strike. The seller of each contract takes the opposite side: a call seller agrees to deliver the asset if the buyer exercises, and a put seller agrees to buy it. Buying a call is bullish and buying a put is bearish. Selling a put is bullish and selling a call is bearish (or at least not bullish), because the seller keeps the premium when the market does not move the way the buyer hoped.

Call vs. put: the four basic positions

Every option trade combines a contract type (call or put) with a direction (buy or sell), giving four starting positions:

• Long call (buy a call): You expect the price to rise. Your maximum loss is the premium paid. Your profit grows as the price climbs above the strike plus the premium.
• Long put (buy a put): You expect the price to fall. Your maximum loss is the premium paid. Your profit grows as the price drops below the strike minus the premium, up to the point where the asset reaches zero.
• Short call (sell a call): You expect the price to stay flat or fall. Your maximum profit is the premium collected. If the price rises above the strike, you may have to sell the asset at the strike, and the loss on an uncovered position has no ceiling.
• Short put (sell a put): You expect the price to stay flat or rise. Your maximum profit is the premium collected. If the price falls below the strike, you may have to buy the asset at the strike, even though it is worth less in the market.

On a payoff graph, a long call is flat below the strike, at a loss equal to the premium, and slopes upward to the right above it. A long put is the mirror image. The short versions flip each line upside down: a flat profit line equal to the premium that turns down once the price moves through the strike.

For standard US equity options, one contract usually covers 100 shares, so a premium quoted at $3.00 means $300 per contract.

Writing, covered and naked

In options markets, writing an option simply means selling it to open a position. The writer receives the premium up front and takes on an obligation that lasts until the contract expires, is closed or is assigned.

A written option is covered when the seller already holds what the contract could require. For a call, that means owning the underlying shares. For a put, it usually means holding enough cash to buy the shares at the strike (a cash-secured put) or holding an offsetting short stock position. A written option is naked, or uncovered, when the seller has no such position. If a naked call is exercised, the writer must buy shares at the current market price in order to deliver them at the lower strike.

Because the potential losses are large, brokers typically require margin for uncovered positions and restrict naked option writing to clients approved for the highest options trading levels.

Selling put options

A put seller is betting that the underlying will finish above the strike. If it does, the buyer has no reason to exercise, because the shares can be sold for more on the open market. The option expires worthless and the seller keeps the premium. If the price falls below the strike, the buyer can exercise, and the seller must buy the shares at the strike. The seller’s breakeven is the strike minus the premium received.

Example: short put

Hypothetical figures; assumes one contract of 100 shares, held to expiration, no commissions.

You sell a $95 put on stock ABC and collect a $3.00 premium, which is $300 per contract. Your breakeven is $92 ($95 minus $3).

• ABC closes at $100: The put expires worthless. You keep $300.
• ABC closes at $93: You are assigned and buy 100 shares at $95 when they are worth $93. The $2 per share shortfall is offset by the $3 premium, leaving a $100 gain.
• ABC closes at $88: You buy at $95 shares worth $88. That is a $7 per share shortfall minus the $3 premium, so you lose $400.
• ABC goes to $0: You lose $92 per share, or $9,200.

The buyer’s worst case is losing the $300 premium. The seller’s worst case is large but finite, because a stock cannot fall below zero.

Some traders sell puts at a strike where they would be willing to own the stock anyway. If they are assigned, their effective purchase price is the strike minus the premium. That only works if the cash to buy the shares is set aside. Otherwise, assignment can trigger a margin call.

Selling call options

A call seller is betting that the underlying will finish below the strike. If it does, the call expires worthless and the seller keeps the premium. If the price rises above the strike, the buyer can exercise and the seller must deliver shares at the strike. The breakeven is the strike plus the premium.

Example: naked short call

Hypothetical figures; assumes one contract, held to expiration, no commissions, no shares owned.

You believe stock XYZ is heading lower and sell a $70 call for a $6.20 premium, collecting $620. Your breakeven is $76.20.

• XYZ closes at $65: The call expires worthless. You keep $620.
• XYZ closes at $74: You are assigned. You buy 100 shares at $74 and deliver them at $70, which costs $4 per share. After the $6.20 premium, you keep $220.
• XYZ closes at $85: You buy at $85 and deliver at $70, a $15 per share cost. After the premium, you lose $880.
• XYZ closes at $120: You lose $43.80 per share, or $4,380.

Warning

A naked call caps your profit at the premium but leaves your loss open-ended, because there is no upper limit on how high a price can go. A takeover announcement or an earnings surprise can gap a stock far above the strike overnight, before a stop or an exit order has a chance to work.

Writing covered calls

A covered call means selling calls against shares you already own, generally one contract per 100 shares. If the call is exercised, you deliver shares you hold instead of buying them in the market, which removes the unlimited-loss problem of the naked call. Buying the stock and writing the call at the same time is called a buy-write.

Hypothetical example, continuing from above: you own 100 XYZ shares bought at $68 and sell the $70 call for $6.20.

• XYZ rises to $85: Your shares are called away at $70. You make $2 per share on the stock plus $6.20 in premium, or $820 in total. You give up the gain above $70.
• XYZ stays at $68: The call expires. You keep the shares and the $620.
• XYZ falls to $60: You keep the shares, which have lost $8 each. The premium cuts that loss to $1.80 per share.

The trade-off is plain: the premium adds income in flat markets and cushions small declines, but it caps your upside and does not protect against a deep drop in the stock.

Assignment, early exercise and closing a position

The buyer decides whether to exercise, and the seller has no say in that decision. US equity options are generally American style, which means the buyer can exercise on any business day before expiration, not only at the end. Early exercise is most likely when an option is deep in the money or, for calls, just before an ex-dividend date. Index options are often European style, which means they can only be exercised at expiration.

An option seller does not have to wait for expiration or assignment. You can buy back the same contract (buy to close) at any time the market is open, locking in whatever gain or loss exists at that moment. A buyer can also sell to close instead of exercising, which captures the remaining time value that exercising would give up.

What are the risks of selling options?

Option sellers benefit from time decay: all else equal, an option loses value as expiration approaches, and that lost value accrues to the seller. That steady edge comes with several risks:

• Adverse price moves. A short call loses as the price rises. A short put loses as the price falls. Losses grow roughly share for share once the price passes the breakeven.
• Volatility increases. Rising implied volatility raises option prices, so a short position can show a loss even if the underlying has barely moved.
• Margin and assignment. Brokers set margin requirements for short options and can raise them as a position moves against you. Assignment on a naked call leaves you short stock, and assignment on a put leaves you holding shares you must pay for.
• Asymmetry. You collect a small, fixed amount in exchange for a much larger potential loss. One bad trade can erase many winning ones.

Before opening any short option, decide on the price or loss level at which you will buy it back or hedge it, and size the position so that loss is tolerable.

When to sell a call vs. a put

Sell a call when you expect the underlying to stay below the strike through expiration, either because you are bearish or because you expect a stalled rally. Selling it covered, against shares you own, suits a neutral to mildly bullish view where you are willing to sell at the strike.

Sell a put when you expect the underlying to stay above the strike, either because you are bullish or because you expect support to hold. It is especially suited to cases where you would accept owning the shares at the strike minus the premium.

Neither trade is a forecast of a big move. When you expect a large rally, buying a call gives you uncapped upside. When you expect a sharp fall, buying a put does the same on the downside. Selling options pays when the market moves less than the buyer needs it to.

Selling puts and calls together, and other strategies

Sellers often combine short options with long ones to limit risk, or pair calls and puts to profit from a range:

• Bull put spread: Sell a put and buy a lower-strike put. The long put caps the loss if the price collapses, for a smaller net premium.
• Bear call spread: Sell a call and buy a higher-strike call. The long call caps the otherwise unlimited upside risk.
• Iron condor: Combine a bull put spread and a bear call spread. This profits if the underlying stays between the two short strikes, with defined risk on both sides.
• Short straddle and short strangle: Sell a call and a put at the same strike (straddle) or different strikes (strangle) without protection, collecting two premiums with naked risk in both directions.
• Calendar spread: Sell a near-term option and buy a longer-dated one at the same strike, profiting as the near-term option loses value faster.

FAQs

The Bottom Line

Traders weighing whether to sell calls or puts are betting the market will move less than the buyer needs. Selling a put suits a trader willing to own shares at the strike minus the premium, and covered calls suit a neutral to mildly bullish view. Before opening any short option, set the price or loss level for buying it back or hedging, and size the position so that loss is tolerable.