What it means
A put is the mirror image of a call option. The owner of a put wants the underlying price to fall, because the right to sell at a fixed price becomes more valuable the further the market price drops below it.
The seller of the put takes the opposite side, collecting the premium in exchange for the obligation to buy at the strike if asked. In equity markets a standard contract covers 100 shares, so a quoted premium of $3 costs $300 in total.
The buyer's maximum loss is that premium, whatever happens, which is what makes puts usable as insurance. The seller's risk is far larger, because the asset can keep falling towards zero.
The most common business use is protection rather than speculation. A founder holding a concentrated position after a lock-up expires, or a fund manager who cannot sell without moving the market, can buy puts to set a floor under the value of the position while keeping the upside.
The premium is the cost of that floor and behaves much like an insurance payment. Value has two parts.
Intrinsic value is how far the option is in the money, which for a put is the strike price minus the market price whenever that difference is positive; time value is the extra amount buyers pay for the chance of further movement before expiry. Time value erodes as expiry approaches, which is why a put held too long can lose money even when the directional view was correct.
Two variants matter in practice. American-style puts can be exercised at any time before expiry while European-style puts can be exercised only on the expiry date, and a protective put held alongside the shares is a hedge whereas a put bought without owning the asset is a directional bet.
Selling puts, often called writing them, generates premium income but commits the seller to buying the asset at the strike if the price falls.
In practice
Real-world examples.
Example
A founder whose lock-up expires six months after an IPO cannot sell without signalling doubt to the market. She buys puts struck 15% below the current price covering half her holding, capping her downside on that half for a premium of about 4% of its value, while keeping any further upside.
Example
An airline's treasury team holds a large equity stake in a supplier taken as part of a settlement. Rather than sell into a thin market, it buys twelve-month puts to protect the carrying value on its balance sheet through an uncertain trading period.
Example
A hedge fund analyst concludes that a listed retailer's inventory is badly overstated and that a writedown is coming. Instead of shorting the shares, which would expose the fund to unlimited losses, the fund buys puts, capping the downside at the $1.2 million premium paid.
Think of it
“Put option is the right to sell-you can sell the asset at the agreed price if you want.
Formula
Calculation
Put buyer payoff at expiry = max(strike price - market price, 0) x contract size - premium paid. Breakeven price = strike price - premium per share.
An investor buys one three-month put on a share at a strike of $50, paying a premium of $3 per share. One contract covers 100 shares, so the outlay is 100 x $3 = $300, and the breakeven is $50 - $3 = $47 per share.
At expiry the share trades at $38. Intrinsic value is $50 - $38 = $12 per share, so the contract is worth 100 x $12 = $1,200. Net profit is $1,200 - $300 = $900, a return of $900 / $300 = 3.0, or 300% on the amount risked. Had the share instead finished at $52, the put would expire worthless and the loss would be the full $300.Case study
Seen in the real world.
The following is an illustrative and entirely fictional example. Vantridge Foods, an invented listed producer, held a 9% stake in a smaller listed distributor worth roughly $18 million, acquired years earlier and now sitting in a volatile part of the market. The board wanted to keep the strategic relationship but could not accept the earnings volatility the stake introduced.
The treasurer bought six-month protective puts struck about 10% below the market price, covering the whole holding, at a premium of roughly 3% of the position value, or about $540,000. When the distributor's shares fell 28% after a profit warning, the puts gained enough value to offset most of the decline below the strike, and Vantridge kept the stake and the relationship intact.
In this illustrative story the board treated the premium as an insurance line in the budget rather than as a trading loss. The fictional lesson is that a put converts an unpredictable exposure into a known, budgeted cost, which is often the point of buying one.
Watch out
Common mistakes.
- Thinking a put must be exercised to be profitable, when in practice most option positions are closed by selling the contract back into the market before expiry.
- Ignoring time decay and buying long-dated protection for a short-term worry, paying for months of time value that will never be used.
- Assuming that being right about the direction guarantees a profit, when the share must fall past the breakeven of strike minus premium before the buyer makes anything.
Questions
People also ask.
What is the most a put buyer can lose?
The premium paid, which is fixed and known at the moment of purchase, no matter how the underlying price moves.
How is buying a put different from short selling?
A put caps the loss at the premium and expires on a fixed date, while a short sale has theoretically unlimited loss and requires borrowing the asset.
Why would anyone sell a put?
To collect the premium as income, usually when they would be content to own the asset at the strike price anyway, though the risk if the price collapses is substantial.
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