Delta is one of the most important "Greeks" in options trading. It measures how much an option's price is expected to move for every $1 move in the underlying stock price. Delta ranges from 0 to 1 for calls (and 0 to -1 for puts).
Delta as a Probability Proxy: Delta can also be interpreted as the approximate probability that an option will expire in-the-money. A 0.30 delta put has roughly a 30% chance of being assigned. A 0.20 delta put has roughly a 20% chance of ending up ITM.
For Wheel Traders: Delta is the primary tool used to select strike prices. Most wheel traders sell puts and covered calls in the 0.20-0.35 delta range, balancing premium income against the risk of assignment or being called away.
Delta and Position Management: When a short put's delta rises above 0.50 (i.e., it goes deep ITM), many traders roll the position to avoid assignment, as the option now behaves more like owning the stock outright.
Examples of Delta in Action
- 1A 0.30 delta put moves $0.30 for every $1 the stock drops — and has roughly a 30% probability of expiring ITM.
- 2Selling a 0.20 delta CSP means there is an ~80% chance the put expires worthless and you keep the full premium.
- 3A deep ITM put with a -0.80 delta is "acting like stock" and carries significant directional risk.