Skip to content

Greeks enough to operate

You do not need a textbook on every Greek. For credit spreads, delta does most of the daily work; theta and implied volatility explain why time and events matter.

Not financial advice

Greeks are model-based estimates. They are guides, not guarantees.

Delta — your strike dial

Delta answers two related questions:

  1. Roughly how much the option’s price moves if the stock moves $1.
  2. A rough sense of how likely the option is to finish in the money — useful, not a promise. [verified] as a widely taught heuristic.

When you sell premium, traders often talk in deltas such as “a 20-delta put” or “a 30-delta call.” Many education sources discuss short strikes in about the 0.15–0.30 absolute-delta band:

  • Closer to 0.15 → usually further out of the money, less premium, tested less often.
  • Closer to 0.30 → more premium, tested more often.

Your exact band belongs in a written policy ([operator preference]). Liquidity and the width of the spread still matter more than any single magic number.

The long option in a spread is simply your insurance further out of the money. Pick it so the max loss (\(W - C\)) is a dollar amount you already accepted.

Theta — why waiting can help (until it does not)

Theta describes time decay. If you are short premium and the stock cooperates, time often works in your favor. A spread also has a long leg, so the benefit is partial — not free money.

Near expiration, prices can move sharply around the short strike. That is one reason many people prefer monthly expirations for calm income processes, and size weeklies smaller. See Weekly vs monthly.

Implied volatility — the “how nervous is the market?” dial

Implied volatility (IV) is the volatility the options market is pricing in. Higher IV usually means richer premiums and a market that expects bigger swings.

Around earnings, IV often rises beforehand and can fall quickly afterward (“IV crush”). That sounds friendly to sellers — until a gap jumps through your short strike. [verified] as common event behavior. Spruce’s risk proposal therefore suggests sitting out new short premium near earnings unless you have an explicit override process.

What you can skip for now

Deep gamma scalping, vol-surface modeling, and rho. Revisit later if you manage complex books.

A short pre-entry habit

Before you click send at the broker, be able to say out loud:

  1. My short strike’s delta (or % out of the money) is _ because _.
  2. My max loss in dollars is ____.
  3. My expiration choice is monthly / weekly because ____.
  4. I am not selling naked risk “because the delta looked fine.”

What to do next

Weekly vs monthly, then the defined-risk overview.

Sources

Not financial advice. Verify broker rules yourself.