Put option explained: definition, mechanics, uses

By Ken Chigbo, Founder, KenMacro. Published 2026-05-13.

What is put option?

A put option is a contract between two parties referencing an underlying asset such as a stock, index, currency pair or commodity. The buyer pays a premium upfront in exchange for the right to sell the underlying at a pre-agreed strike price, either at expiry (European style) or at any point before it (American style). The seller, also called the writer, receives that premium and accepts the obligation to purchase the asset at the strike if the buyer exercises. Puts gain value as the underlying falls, as implied volatility rises, and lose value with the passage of time, a property known as theta decay.

How traders use put option

Retail traders use puts in three main ways. First, as directional bets on a fall: buying a put is a defined-risk way to express a bearish view, with maximum loss capped at the premium paid. Second, as portfolio insurance: holders of long equity or index exposure buy out-of-the-money puts to hedge drawdown risk, accepting the premium as the cost of protection. Third, as income generation: cash-secured put selling collects premium and obliges the seller to buy the underlying at strike if assigned, which suits traders happy to own the asset at that level. Institutional desks combine puts with calls and futures in spreads, collars and risk reversals to shape exposure around catalysts like FOMC meetings, CPI releases and earnings.

Worked example of a put option

Suppose a trader buys one put on a stock trading at 100, with a strike of 95, expiring in 30 days, for a premium of 2 per share. The contract covers 100 shares, so the total cost is 200. If the stock closes at 90 at expiry, the put is worth 5 intrinsically (95 minus 90), giving a payoff of 500 and a net profit of 300. If the stock closes anywhere at or above 95, the put expires worthless and the trader loses the full 200 premium. Break-even sits at 93, the strike minus premium paid.

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Frequently asked

What is the difference between a put option and a call option?

A put option gives the holder the right to sell the underlying at the strike price, profiting when the asset falls. A call option gives the right to buy at the strike, profiting when the asset rises. Both involve paying a premium for the right, and both have a corresponding seller who collects that premium and assumes the obligation. Puts are typically used for bearish views or downside hedging, calls for bullish views or upside participation.

Can you lose more than the premium on a put option?

If you buy a put, your maximum loss is strictly limited to the premium paid, regardless of how the underlying moves. If you sell or write a put without a hedge, losses can be substantial, since the underlying can fall toward zero while you are obliged to buy at the higher strike. Cash-secured put sellers set aside the full strike value, which caps risk at strike minus premium received, multiplied by contract size.

When should a trader buy a put option?

Buying a put suits situations where a trader expects a meaningful decline in the underlying within a defined timeframe, or wants to hedge an existing long position against drawdown. Puts are most effective when implied volatility is reasonable relative to expected realised moves, since overpaying for volatility erodes returns even if the directional view proves correct. The desk treats puts as a defined-risk instrument suited to event-driven exposure around macro releases or earnings catalysts.

What does it mean for a put option to be in the money?

A put option is in the money when the current price of the underlying sits below the strike price, giving the option intrinsic value equal to strike minus spot. It is at the money when the underlying trades at or very near the strike, and out of the money when the underlying is above the strike. Only in-the-money puts carry intrinsic value at expiry; out-of-the-money puts expire worthless.

Educational analysis only. Past performance does not guarantee future results. Manage risk against your own portfolio.