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Delta

How much an option's price moves for a one-dollar move in the underlying. It doubles as a rough probability of finishing in the money.

Updated 2026-09-05

Delta measures how much an option's price changes for a one-dollar move in the underlying. A delta of 0.60 means the option gains about 60 cents when the stock gains a dollar. Calls run from 0 to 1, puts from 0 to −1.

It has a second reading that is more useful than the first: delta approximates the probability the option finishes in the money. A 0.30-delta call is roughly a 30 percent chance of expiring with value. That reframes a cheap out-of-the-money option honestly, as a low-probability bet priced accordingly rather than as a bargain.

Delta also tells you the equivalent share exposure. A 0.60-delta call on 100 shares behaves roughly like owning 60 shares, which is how a position's real market exposure is measured when options are involved.

See also

  • Gamma and theta — Gamma is how fast delta changes; theta is how much value the option loses per day. Together they are why an option buyer is racing a clock.
  • Strike price — The price at which an option can be exercised. Its distance from the current price determines almost everything about how the option behaves.
  • Option — A contract giving the right, but not the obligation, to trade something at a set price before a set date. The buyer has the right and the seller has the obligation.

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Educational content, not investment advice. Angie explains how a valuation is built so you can judge it yourself. What you do with that is your call.

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