Separate the amount without forecasting
Suppose the underlying is 108, the call strike is 100 and the premium per notional unit is 12. Intrinsic value is 8 and extrinsic value is 4. This is an arithmetic decomposition of one price, not two independent payments. If the contract multiplier differs from one, all monetary amounts must be rescaled consistently. Do not compare a per-share premium with the full contract value and call the difference extra income. First establish the quotation unit and contract size.
Later, suppose the premium is 10. A buyer who paid 12 would have a result of −2 per unit before costs if the position could be closed at 10. Positive intrinsic value does not remove that difference. The new value is a scenario, not a calculation from market behaviour. It shows why knowing the position relative to the strike does not determine the purchase result: the price paid and the available exit price matter. A matching order is assumed only for arithmetic.
What enters a pre-expiry valuation
OIC lists the underlying price, strike, time, volatility, dividends and interest rate among premium factors.[28](#source-cm-premium) The direction of one factor cannot automatically become a forecast of the final price when the others also change. For example, approaching expiry and changing expected volatility may affect the same premium simultaneously. When comparing two options, check not only call or put, but also expiry, strike, multiplier, underlying and exercise terms. Similar names do not make contracts identical.
Time value is not a linear subscription fee that must decline by the same amount every calendar day. A general ceteris-paribus tendency and the actual path of an observed price are different claims. The market may reprice uncertainty while the underlying moves. The SEC also connects premium with time and volatility.[27](#source-cm-options) Therefore, “I correctly guessed the direction” does not by itself test the purchase result or prove that a negative result means the quote was wrong.
A model price is not an executable quote
If a valuation model is used, state its inputs and assumptions. A theoretical value may differ from the best bid and ask, and there need not be an executable order at the midpoint. The difference between model and market is not a guaranteed profit opportunity without costs, constraints and model risk. This material does not recommend a trading model; it shows that the price of a right is determined by the contract and market state, not by one intrinsic-value formula.
As a check, take two calls with the same intrinsic value but different expiries. Equality of that component does not require equal premiums. Conversely, the same premium with different strikes and multipliers can have entirely different exercise consequences. Reconstruct every parameter before comparing. The [issuer and security identifier guide](/guides/issuer-and-security-identifiers/) identifies the object precisely, while the [derivatives introduction](/guides/futures-and-options/) distinguishes a right from an obligation.
Price and explanation of its change
A known premium decomposition does not by itself identify which factor caused an observed move. That requires comparable inputs and a specified model. If expiry, underlying price and uncertainty assessment all changed, the whole difference cannot be attributed to time. Decomposing an amount and establishing causation are separate tasks.
Also separate a market premium from a model value. For a calculated figure, identify assumptions, date and units. No trade at that figure does not make the intrinsic-value arithmetic wrong: calculation and available execution answer different questions. In a teaching text, state what is observed and what is modelled. Leave an unverified cause as a hypothesis rather than presenting it as the exact explanation of a future price.