What Is Charm in Options? Delta Decay Explained
Charm is the quiet greek that moves markets on days when nothing appears to be happening.
What is charm in options?
Charm measures how much an option delta changes purely from the passage of time. As expiration approaches, out of the money options lose delta and in the money options gain delta, which forces dealers to adjust hedges even when the underlying price has not moved.
How does charm create expiration drift?
Dealers hedging a large book must unwind hedges against decaying out of the money options as expiration nears. That unwind is directional and predictable, producing a slow persistent drift toward the heaviest strikes through the final sessions before a major expiration.
When are charm flows strongest?
Charm flows peak into monthly and quarterly expirations, when the largest concentration of open interest sits on a single date. Charm pressure also strengthens through each afternoon as the trading day runs out, which is why quiet mornings often give way to a steady one directional afternoon grind.
Frequently asked questions
Can a retail trader see charm flows directly?
Charm flow is not published anywhere. A trader infers charm pressure from the open interest distribution and the time remaining, which is what a positioning terminal calculates.