Call Options Explained: Payoffs, Breakevens, and Buying vs Selling Calls

A call option gives its buyer the right to buy 100 shares of a stock at a fixed price, the strike, on or before the expiration date. The buyer profits at expiration only if the stock finishes above the strike by more than the premium paid; the seller of the call keeps the premium if it doesn’t.

In short: buying a call costs the premium (quoted per share, times 100). The breakeven at expiration is the strike plus the premium. The buyer’s maximum loss is the premium, and the maximum gain is unlimited in theory. The writer of the call receives the premium, has a maximum gain equal to that premium, and takes on a loss that grows without limit if the stock rises and the writer doesn’t own the shares.

The question people actually ask

“If I think a stock is going up, why not buy a call instead of the shares? It’s so much cheaper.” The answer is that a call is cheaper because it is a different bet. Owning shares pays you if the stock rises at any point and at any speed. A call pays you only if the stock rises far enough, by a specific date. Miss either condition and the premium can be lost entirely.

How a call works

A call has a strike price and an expiration date. At expiration, its value is simple:

If the stock is above the strike, the call is worth the stock price minus the strike (per share).
If the stock is at or below the strike, the call is worth nothing.

That amount is the call’s intrinsic value at expiry. Before expiration, a call also carries time value, which is why its price is usually higher than its intrinsic value. Both parts are covered in how option premiums work.

Whether a call is above or below the strike has its own vocabulary: in the money, at the money, and out of the money, explained in in the money vs out of the money.

Buying a call: a worked example

Hypothetical Maple Widgets Inc. trades at $50. A call with a $50 strike expiring in about 60 days is quoted at $2.60.

Cost: $2.60 x 100 = $260 (ignoring commissions and fees).
Breakeven at expiration: $50 + $2.60 = $52.60.
Maximum loss: $260, if Maple is at or below $50 at expiration.
Maximum gain: no fixed limit.

Profit or loss at expiration:

Maple at expiry	Call value per share	Contract value	Profit or loss	Return on $260
$40	$0	$0	-$260	-100%
$45	$0	$0	-$260	-100%
$50	$0	$0	-$260	-100%
$52.60	$2.60	$260	$0	0%
$55	$5.00	$500	+$240	+92%
$60	$10.00	$1,000	+$740	+285%
$70	$20.00	$2,000	+$1,740	+669%

Two things stand out. Below the strike, the loss stops at $260 no matter how far the stock falls. Above the breakeven, every $1 rise in the stock adds $100 to the position.

The same view, compared with owning the shares

Buying 100 Maple shares at $50 costs $5,000. Here is how the two compare at expiration:

Maple at expiry	100 shares: P/L	Call: P/L
$40	-$1,000 (-20%)	-$260 (-100%)
$45	-$500 (-10%)	-$260 (-100%)
$50	$0 (0%)	-$260 (-100%)
$55	+$500 (+10%)	+$240 (+92%)
$60	+$1,000 (+20%)	+$740 (+285%)

The call loses less in dollars on a big fall, because the most it can lose is $260. But in percentage terms it is far more volatile: a flat stock is a 0% outcome for the shareholder and a 100% loss for the call buyer. This is what people mean by leverage. It amplifies both directions, and with a deadline attached.

(Shareholders would also receive any dividends paid during the period; call holders do not.)

Closing a call before expiration

You don’t have to hold a call to expiration. Most holders close by selling the call back in the market. Its price then reflects both intrinsic value and remaining time value.

Using a Black-Scholes model with 30% volatility and a 4% interest rate (assumptions, not market data), the same $50 call with 60 days left is worth roughly:

Maple price today	Model call value	Contract value
$48	$1.63	$163
$50	$2.58	$258
$52	$3.80	$380
$55	$6.04	$604

So a quick $2 rise in the stock lifts the call by about $1.20 per share, roughly 47% on the contract. A $2 fall cuts it by about 37%. And if the stock just sits at $50, the call slowly loses value as time passes. That decay is the subject of theta and time decay.

You can also exercise the call: pay $50 x 100 = $5,000 and receive 100 shares. Exercising before expiration throws away any remaining time value, so selling the call is usually worth more than exercising it. The main exception relates to dividends, covered in how exercise and assignment work.

Writing (selling) a call

The other side of the trade is the call writer. The writer receives the $260 premium up front and takes on the obligation to sell 100 shares at $50 if assigned.

Writer’s profit or loss at expiration, same contract:

Maple at expiry	Writer’s P/L (no shares owned)
$40	+$260
$50	+$260
$52.60	$0
$55	-$240
$60	-$740
$80	-$2,740
$100	-$4,740

The writer’s best case is keeping $260. The worst case has no ceiling, because there is no ceiling on how high a stock can go.

Covered vs naked calls

A covered call is written by someone who already owns 100 shares per contract. If assigned, the writer delivers the shares they already have. The upside on the shares is capped at the strike, but the call’s loss is offset by the stock’s gain. Covered calls are a strategy of their own, with risks that are easy to underestimate.
A naked (uncovered) call is written without owning the shares. If assigned, the writer must buy shares at the market price to deliver at the strike. Brokers require significant margin and the highest approval level for naked calls, precisely because the loss is open-ended.

What moves a call’s price

At expiration, only the stock price and the strike matter. Before expiration, several inputs feed the premium:

Stock price: higher stock price, higher call value.
Time to expiration: more time, more value, all else equal.
Implied volatility: higher expected volatility, higher call value. Calls can lose value after an earnings report even when the stock rises, if volatility expectations collapse.
Interest rates: higher rates slightly raise call values.
Dividends: expected dividends slightly lower call values, because the stock price drops by roughly the dividend on the ex-dividend date.

What can go wrong

Right direction, wrong timing. The stock rises after your call expires. The call pays nothing for being early.
Right direction, not enough. In the table above, a rise from $50 to $52 is a 4% gain for a shareholder and a loss for the call buyer at expiration.
Volatility drops. A call bought when implied volatility is high can lose value even if the stock moves your way.
Wide bid-ask spreads. Buying at the ask and selling at the bid can cost a noticeable share of a small premium.
For writers: unlimited loss on naked calls, early assignment (especially before ex-dividend dates), and gaps on takeover news.

Common questions

Can I lose more than I paid for a call?

Not as a buyer. If you buy a call and do nothing else, the most you can lose is the premium plus commissions and fees. The exception is what happens at expiration: if the call finishes in the money, it can be exercised automatically, and you’d then own 100 shares per contract that you have to pay for. Those shares can lose value like any other stock position. Writers are a different story: a naked call writer can lose many times the premium received.

Why does my call lose money when the stock goes up a little?

Because two things are moving at once. The stock’s rise adds value, but each day that passes takes some time value away, and a drop in implied volatility can take away more. A small move in your favour can be outweighed by the passage of time. At expiration, the stock has to be above the breakeven (strike plus premium), not just above the strike, for the trade to be profitable.

Is a call the same as buying the stock on credit?

No. Buying shares on margin gives you the shares, dividends, and voting rights, with interest charged on the loan and no expiry date. A call gives you none of those, only a right that expires. A margin position can be held as long as you meet margin requirements; a call ends on its expiration date whether you’re right or not.

How many shares does one call control?

A standard US or Canadian equity call covers 100 shares. Contracts can be adjusted after corporate actions such as some stock splits, in which case the deliverable may be different, so check the contract details before trading an unusual-looking option.

The takeaway

A call is the right to buy at the strike until expiration. Buying one risks the premium for a payoff that starts only above strike plus premium. Writing one earns the premium in exchange for giving up the upside, and an uncovered writer can lose far more than the premium collected. The arithmetic is simple, but the deadline makes the outcome unforgiving.