This page is for the options calculation section. It focuses on long call, long put, short call, short put, one-step binomial pricing, and plug-in Black-Scholes.
Graph part: be ready to draw the long call payoff graph and the long put payoff graph. You do not need short-call or short-put payoff graphs, and you do not need long-call or long-put profit graphs.
The biggest idea is: payoff is the value at expiration. Profit adjusts payoff for the premium.
Starts flat at zero until the strike price, then rises upward.
Starts high when the stock price is very low, then declines to zero at the strike and stays flat after that.
The most important relationship is shown below. For long positions, profit equals payoff minus premium. For short positions, premium is received up front, so profit equals premium minus the exercise loss later.
| Position | Rule | Example idea |
|---|---|---|
| Long Call | Benefit when ST > X | If X = 50, premium = 4, ST = 60, payoff = 10, profit = 6 |
| Long Put | Benefit when ST < X | If X = 50, premium = 3, ST = 40, payoff = 10, profit = 7 |
| Short Call | Keep premium if stock does not rise above X | If X = 50, premium = 4, ST = 60, profit = 4 − 10 = −6 |
| Short Put | Keep premium if stock does not fall below X | If X = 50, premium = 3, ST = 40, profit = 3 − 10 = −7 |
Given: S0 = 40, Su = 50, Sd = 30, X = 35, r = 8%
| # | Likely question type | Main skill | Notes |
|---|---|---|---|
| 1 | Long call payoff and profit | Know payoff first, then subtract premium | May also ask for break-even idea |
| 2 | Long put payoff and profit | Know payoff first, then subtract premium | Good when stock falls below strike |
| 3 | Short call payoff and profit | Premium received minus exercise loss | Watch sign carefully |
| 4 | Short put payoff and profit | Premium received minus exercise loss | Watch sign carefully |
| 5 | One-step binomial | Find Cu, Cd, p, and C0 | Keep it very mechanical |
| 6 | Black-Scholes plug-in | Identify inputs and substitute correctly | No big derivation needed |
| 7 | Draw long call payoff graph | Flat until strike, then rising | Payoff graph only |
| 8 | Draw long put payoff graph | Declining to strike, then flat at zero | Payoff graph only |