What Is a Put Option?

Understand how put options work, calculate your potential profit and loss, and learn when buying or selling puts makes sense for your portfolio.

MT
Written by Michael Torres, CFA
Senior Financial Analyst
JW
Fact-checked by Dr. James Wilson, PhD
Options Strategy Researcher
Options BasicsFact-Checked

Input Values

$

The current market price of the underlying stock.

$

The price at which you have the right to sell the stock.

$

The cost you pay per share to buy the put option.

Each contract represents 100 shares of the underlying stock.

$

Your estimated stock price at option expiration.

Results

Total Cost of Put$250.00
Intrinsic Value at Expiry
$0.00
Net Profit / Loss
$0.00
Return on Investment0.00%
Breakeven Stock Price-$2.50
Maximum Possible Profit-$250.00
Results update automatically as you change input values.

What Is a Put Option?

A put option is a financial contract that gives the buyer the right, but not the obligation, to sell a specific number of shares of an underlying asset at a predetermined price (the strike price) before or on a specific expiration date. The buyer pays a premium to the seller (writer) of the put option for this right. Put options increase in value when the price of the underlying stock decreases, making them a tool for bearish speculation or portfolio protection.

In the U.S. and Canadian stock markets, one standard put option contract represents 100 shares. If you buy a put option with a strike price of $95 and the stock falls to $80, you can exercise the put to sell your shares at $95 each, even though they are only worth $80 on the open market. This difference, minus the premium paid, is your profit.

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Put Option in Plain English

Think of a put option like an insurance policy for your stock. You pay a small premium now for the right to sell your shares at a guaranteed price later, protecting you if the stock drops.

How Put Options Work: Step by Step

The Mechanics of a Put Option Trade

1
Select the Underlying Stock
Choose the stock you want to buy a put option on. This could be a stock you already own (protective put) or one you believe will decline in price (speculative put).
2
Choose a Strike Price
The strike price is the price at which you can sell the shares. A higher strike price costs more premium but provides more protection or profit potential.
3
Select an Expiration Date
Put options have a fixed expiration date. Longer-dated options cost more but give the stock more time to move in your favor.
4
Pay the Premium
You pay the option premium to the seller. This is the maximum amount you can lose on the trade if the put expires worthless.
5
Monitor the Position
If the stock drops below the strike price, the put becomes profitable. You can exercise the option, sell it on the open market, or let it expire.

Put Option Profit and Loss Formulas

Put Option Buyer Profit/Loss
Profit = max(Strike Price - Stock Price at Expiry, 0) - Premium Paid
Where:
Strike Price = The price at which you can sell the shares
Stock Price at Expiry = The market price of the stock when the option expires
Premium Paid = The cost of buying the put option per share
Breakeven Price for Put Buyer
Breakeven = Strike Price - Premium Paid
Where:
Strike Price = The option's strike price
Premium Paid = Premium paid per share for the put option
Maximum Profit for Put Buyer
Max Profit = (Strike Price - Premium Paid) × 100 × Contracts
Where:
Strike Price = The option's strike price
Premium Paid = Premium cost per share
Contracts = Number of option contracts

Put Option Example with Real Numbers

Buying a Put Option on XYZ Stock
Given
Stock Price
$100
Strike Price
$95
Premium Paid
$2.50 per share
Contracts
1 (100 shares)
Stock at Expiry
$85
Calculation Steps
  1. 1Total cost of put = $2.50 × 100 = $250
  2. 2Intrinsic value at expiry = $95 - $85 = $10 per share
  3. 3Total intrinsic value = $10 × 100 = $1,000
  4. 4Net profit = $1,000 - $250 = $750
  5. 5Return on investment = $750 / $250 = 300%
  6. 6Breakeven price = $95 - $2.50 = $92.50
Result
If XYZ drops to $85, your put option generates a $750 profit (300% return) on a $250 investment. The stock only needs to fall below $92.50 for you to make money.

When to Buy Put Options

  • You believe a stock is overvalued and will decline in price
  • You own shares and want insurance against a downturn (protective put)
  • You want leveraged exposure to a stock's decline without short selling
  • You want to hedge an overall long portfolio during uncertain markets
  • You see technical or fundamental signals pointing to a stock decline
  • You want defined risk: the most you can lose is the premium paid

Put Option Outcomes at Expiration

What Happens to Your Put Option at Expiration
Stock Price vs. StrikeOption StatusActionFinancial Result
Stock well below strikeDeep in the moneyExercise or sell the putSignificant profit minus premium
Stock slightly below strikeIn the moneyExercise or sell if profit exceeds commissionsSmall profit minus premium
Stock equals strikeAt the moneyOption expires worthlessLose entire premium paid
Stock above strikeOut of the moneyOption expires worthlessLose entire premium paid

Buying Puts vs. Short Selling

Both buying put options and short selling allow you to profit from a stock's decline, but they carry very different risk profiles. When you short sell, you borrow shares and sell them, hoping to buy them back cheaper. However, your potential loss is theoretically unlimited if the stock rises. With a put option, your maximum loss is limited to the premium paid, making it a safer way to bet against a stock.

Put Options vs. Short Selling Comparison
FeatureBuying PutsShort Selling
Maximum LossLimited to premium paidTheoretically unlimited
Capital RequiredJust the premium50% margin requirement + maintenance
Time LimitExpires on expiration dateNo expiration (but borrowing costs accrue)
DividendsNo dividend obligationMust pay dividends to share lender
ComplexitySimple one-step tradeRequires margin account and borrow availability

Key Terms Every Put Option Trader Should Know

Understanding put option terminology is essential before placing your first trade. The strike price is the price at which you can sell shares. The expiration date is the last day the option is valid. Premium is the price you pay for the option. Intrinsic value is the amount the option is in the money (strike price minus stock price, if positive). Time value is the portion of the premium above intrinsic value, reflecting the possibility that the option could become more valuable before expiration.

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Risk Reminder

Most options expire worthless. Only risk money you can afford to lose, and always calculate your maximum loss before entering a put option trade. The premium you pay is the most you can lose as a put buyer.

Frequently Asked Questions

A put option is a contract that gives you the right to sell 100 shares of a stock at a specific price (the strike price) before a certain date (the expiration). You pay a premium for this right. If the stock price falls below the strike price, the put option becomes valuable because you can sell shares at the higher strike price. If the stock stays above the strike price, the option expires worthless and you lose the premium.

Sources & References

  • U.S. Securities and Exchange Commission (SEC) - Investor Education
  • Options Clearing Corporation (OCC) - Options Education
  • Chicago Board Options Exchange (CBOE) - Options Strategies
  • Hull, J.C. "Options, Futures, and Other Derivatives" (11th Edition, 2021)

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