Delta, simply: your option's directional exposure

If you learn one option Greek, make it delta. It answers the most basic question you have about any option: how does this thing move when the stock moves?

The plain definition

Delta measures how much an option's price changes for a $1 change in the underlying. A call with a delta of 0.50 gains roughly $0.50 if the stock rises $1 (per share; options control 100 shares, so about $50 per contract). Calls have positive delta (they rise with the stock); puts have negative delta (they rise as the stock falls).

Two ways to read it

Delta does double duty:

• As sensitivity: how much your option's price reacts to the underlying's moves right now.
• As a rough "share equivalent": a 0.50-delta call behaves a bit like owning 50 shares. A near-1.0 delta option moves almost exactly like the stock; a near-0 delta option barely reacts at all.

Many traders also use delta as a loose, informal proxy for the probability an option finishes in-the-money — a handy intuition, even if it isn't exactly a probability.

Why it's the one to start with

Delta turns an option from a mystery into something you can reason about. Before you trade, it tells you how directional your position really is — whether you've got a gentle tilt or something that'll move almost dollar-for-dollar with the underlying. That single number is the foundation everything else (gamma, hedging, position sizing) builds on.

Start with delta. The rest of the Greeks make far more sense once you can feel how your position moves with the market.

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This article is educational and does not constitute investment advice or a recommendation. Options trading involves substantial risk and is not suitable for every investor. Autopilot Options does not guarantee profits or prevent losses. Past performance and historical data do not guarantee future results.