Options explained: calls, puts, and the basics of derivative contracts

An options contract is the right—not the obligation—to buy or sell an underlying asset at a defined price within a defined period. The structural difference from owning the underlying asset is asymmetric: limited downside (the premium paid) for potentially unlimited upside, or vice versa for the seller. Options are the building blocks of nearly every derivative strategy and the foundation of the volatility-risk-premium and tail-hedging frameworks.

What options are

An options contract gives one party (the buyer) the right to take a specific action against another party (the seller, also called the writer) within a defined window. A call option gives the buyer the right to purchase the underlying asset at a defined strike price. A put option gives the buyer the right to sell the underlying asset at a defined strike price. The buyer pays a premium upfront in exchange for the right; the seller receives the premium and accepts the obligation to deliver if the buyer exercises.

The contract specifies four key terms: the underlying asset (a stock, an index, a currency, a commodity), the strike price (the price at which the buyer can buy or sell), the expiration date (when the right expires), and the contract size (typically 100 shares for US equity options). The premium is determined by the market and varies with the underlying price, the time to expiration, the volatility of the underlying, and the prevailing interest rate.

Options trade on exchanges (CBOE, Eurex, ASX) and over-the-counter. Listed equity options in major markets have standardised terms (specific strikes, monthly or weekly expirations, defined contract size) that facilitate liquidity; over-the-counter options can be customised to the specific terms the parties agree.

How calls and puts work

A call option is profitable for the buyer when the underlying price rises above the strike. For a call with strike USD 100 trading at a premium of USD 3, the breakeven for the buyer is USD 103—the strike plus the premium. If the underlying rises to USD 110, the buyer can exercise (buying the underlying at USD 100 and immediately selling at USD 110) for a USD 10 gain less the USD 3 premium, or USD 7. If the underlying stays below USD 100, the option expires worthless and the buyer's loss is the USD 3 premium.

A put option is profitable for the buyer when the underlying price falls below the strike. For a put with strike USD 100 trading at a premium of USD 3, the breakeven for the buyer is USD 97. If the underlying falls to USD 90, the buyer can exercise for a USD 10 gain less the USD 3 premium, or USD 7. If the underlying stays above USD 100, the option expires worthless.

The seller's payoff is the mirror image. The call seller receives the USD 3 premium upfront and bears unlimited upside risk if the underlying rises above the strike; the put seller receives the premium and bears the risk of large losses if the underlying falls toward zero. The asymmetry between the buyer's limited risk and the seller's potentially large risk is the structural feature that makes options different from outright positions in the underlying.

Options can be combined into many positions with different payoff profiles. A long call plus a short call at a higher strike (a call spread) limits both upside and downside; a long put plus a short call at the same strike (a synthetic short) replicates a short position in the underlying; a long call plus a long put at the same strike (a straddle) profits from large moves in either direction. The combinatorial possibilities are large, and entire strategy categories—covered calls, protective puts, iron condors—are defined by specific multi-leg combinations.

What the evidence shows

The empirical structure most relevant to investors is the volatility risk premium: implied volatility (the volatility embedded in option prices) has been on average above realised volatility (the volatility actually experienced by the underlying) over multi-decade samples in major equity markets. The 4–6 percentage-point gap means that selling options has been on average profitable, while buying options has been on average loss-making. The pattern is the basis for the volatility-selling strategy class and the structural cost of put-buying-based tail hedging.

For protective put strategies—buying out-of-the-money puts as portfolio insurance—the long-run cost is typically 1–3% of portfolio value per year, with the protection paying off in the worst drawdowns. The trade-off is favourable for investors who cannot tolerate the deepest drawdowns and unfavourable for investors who can.

For covered-call strategies—selling calls against a long underlying position—the long-run effect is to reduce portfolio volatility and limit upside in exchange for premium income. The strategy underperforms a buy-and-hold equivalent in strong bull markets and outperforms in flat or moderately rising markets. The empirical case is mixed; the strategy is most useful for investors who specifically want the volatility reduction and accept the upside cap.

Limitations and trade-offs

Options are operationally more complex than outright positions in the underlying. The required infrastructure includes options-margin agreements, exercise-and-assignment handling, and risk-management overlays for the multi-leg positions. Retail brokers offer options trading but typically with tiered approval levels that require investors to demonstrate experience before being granted access to the more complex strategies.

The leverage embedded in options positions is meaningful and asymmetric. A long option position can produce profits many times the premium paid, but the maximum loss is limited to the premium. A short option position can produce profits up to the premium received but losses potentially many times the premium. The risk-management implications of short options positions are substantially more demanding than long positions.

Tax treatment of options varies by jurisdiction and by the specific position type. Some positions produce short-term capital gains regardless of holding period; some are subject to specific tax rules (Section 1256 in the US for index options, equivalent rules elsewhere) that differ from straight equity tax treatment. The after-tax case for any options strategy depends on the specific tax position the investor faces.

Options in pfolio

Options are not currently part of pfolio's investable universe. The platform's risk and return analytics apply to underlying equity, fixed income, commodity, currency, and alternatives positions. Investors who use options through their broker can supplement pfolio's analysis with separate options-specific analytics from the broker's tools.

Related articles

• Futures explained: how futures contracts work and why they matter
• The volatility risk premium: why selling volatility has historically been profitable
• Tail risk hedging: practical approaches to limiting catastrophic loss
• Implied vs realised volatility: what option prices say versus what actually happens