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What is the Black-Scholes-Merton formula for a European call option price?

The Black-Scholes-Merton formula for a European call option price is C=S0N(d1)−Xe−rTN(d2)C = S_0 N(d_1) - X e^{-rT} N(d_2). In this formula, S0S_0 is the current stock price, XX is the strike price, rr is the risk-free interest rate, TT is the time to maturity, N(⋅)N(\cdot) is the cumulative distribution function of the standard normal distribution, and d1d_1 and d2d_2 are intermediate variables.

Conditions

  • The option is a European call option.
  • The underlying asset pays no dividends during the life of the option.

Reasoning, step by step

  1. Identify the current stock price S0S_0 and the strike price XX.
  2. Determine the risk-free interest rate rr and the time to maturity TT.
  3. Calculate the volatility σ\sigma of the underlying asset.
  4. Compute the intermediate variables d1d_1 and d2d_2.
  5. Evaluate the standard normal cumulative distribution function N(d1)N(d_1) and N(d2)N(d_2).
  6. Substitute these values into the formula C=S0N(d1)−Xe−rTN(d2)C = S_0 N(d_1) - X e^{-rT} N(d_2) to find the call option price.

Example

The video displays the formula C=S0N(d1)−Xe−rTN(d2)C = S_0 N(d_1) - X e^{-rT} N(d_2) at the top of the page and the instructor handwrites it while explaining that the call option price equals the stock price multiplied by the standard normal distribution at d1d_1, minus the discounted strike price multiplied by the standard normal distribution at d2d_2.

Common misconceptions

  • Confusing the call option formula with the put option formula.
  • Forgetting to discount the strike price XX by the factor e−rTe^{-rT}.
  • Assuming N(d1)N(d_1) and N(d2)N(d_2) are probability densities rather than cumulative probabilities.

Watch the explanation

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Answers are generated from source material and independently checked. Consult the original video or creator if something is unclear.