Options Explained: Calls, Puts & the Greeks
Forwards vs Futures Explained focused on contracts that lock in a future price. Options answer a different risk question: what if you want the right to act, but not the obligation? In interviews, this matters because options are payoff-and-risk instruments, and candidates are expected to connect calls, puts, premium value, moneyness, and the Greeks to real trading decisions.
- An option gives the holder the right but not the obligation to buy (Call) or sell (Put) an underlying asset at a specified strike price (K) before or on the expiry date.
- The buyer pays a premium upfront; the seller (writer) receives this premium and bears the risk.
- Option Premium = Intrinsic Value + Time Value. Time Value = Premium - Intrinsic Value. Decays to zero at expiry (theta decay).
- In-the-money (ITM): Has intrinsic value. At-the-money (ATM): S ā K. Out-of-the-money (OTM): No intrinsic value.
- Long Call profit = max(S - K, 0) - Premium. Long Put profit = max(K - S, 0) - Premium.
- Delta, Gamma, Theta, Vega, and Rho explain how price, time, volatility, and rates change option value and trading decisions.
Options as Payoff-and-Risk Instruments
An option gives the holder the right but not the obligation to buy (Call) or sell (Put) an underlying asset at a specified strike price (K) before or on the expiry date. The buyer pays a premium upfront; the seller (writer) receives this premium and bears the risk.
The big picture is simple: option value comes from intrinsic value and time value, payoff comes from the relationship between spot price and strike price, and the Greeks explain how the option price changes as the market moves.
Option Premium = Intrinsic Value + Time Value. Intrinsic Value (Call) = max(S - K, 0). Intrinsic Value (Put) = max(K - S, 0). Time Value = Premium - Intrinsic Value.
Intrinsic Value, Time Value, and Moneyness
Intrinsic Value is the value that exists when the option has a favourable relationship between the underlying price and the strike price. Time Value is the part of the premium beyond intrinsic value, and it decays to zero at expiry through theta decay.
In-the-money (ITM): Has intrinsic value. At-the-money (ATM): S ā K. Out-of-the-money (OTM): No intrinsic value. OTM options are purely time value and decay fastest in the final weeks before expiry.
Payoff Profiles at Expiry
Payoff profiles show profit or loss across the underlying price range at expiry. A long call and long put are directional options, while spreads and straddles reshape risk and reward using combinations of calls and puts.
Long Call profit = max(S - K, 0) - Premium (unlimited upside, limited downside). Long Put profit = max(K - S, 0) - Premium (profit rises as price falls to zero). Short Call/Put: mirror images - capped gain (premium received), potentially unlimited loss.
The Greeks: How Option Prices Move
The Greeks convert option risk into measurable sensitivities. They show how option value changes with the underlying price, the rate of change in Delta, time decay, implied volatility, and interest rates.
Before TCS earnings, implied volatility might jump from 18% to 28% (+10%). If Vega = ā¹20, the option gains ā¹200. After results, IV crushes to 12% and the option loses ā¹120, so the strategic question is whether the post-results stock move is large enough for intrinsic value gain to beat IV crush loss.
Options Strategies
Options strategies combine calls, puts, strikes, and premiums to shape maximum profit, maximum loss, and the market condition where the structure works best.
Structuring a Options Explained Interview Answer
"Would you be long or short vega before Q3 results?"
Do not stop at "long vega." The stronger answer says: Long vega (long straddle/strangle) - you expect volatility to spike before/after the announcement. After results, IV typically "crushes" - benefiting option sellers (short vega).
Conclusion
Options are best understood as instruments that separate payoff from obligation: calls, puts, premium, moneyness, and payoff profiles define the trade, while the Greeks explain how price, time, volatility, and rates change its risk.
The most frequent error is ignoring time value and volatility after buying options. OTM options are purely time value and decay fastest in the final weeks before expiry, and if stock barely moves after results, IV crush destroys the premium paid.