Greeks Refresher
Delta (Δ) — $ move per $1 in stock. Also ≈ probability ITM.
Gamma (Γ) — rate-of-change of delta. Highest ATM and short-dated.
Theta (Θ) — daily $ time decay. Sellers love it, buyers fight it.
Vega (ν) — $ change per 1pt IV. Long premium = long vega.
Volume vs OI
Volume resets daily and shows today's activity. High volume + low OI = new positioning.
Open Interest is total outstanding contracts. Persistent OI builds = institutional commitment.
Vol > OI on a strike is a clear flag for unusual activity.
IV Skew & Smile
Smile — IV plotted by strike. Curves up at wings = crash risk priced in.
Skew — typically downside puts have richer IV than calls in equities (hedging demand).
Term Structure — IV across expiries. Backwardation (front > back) = stress.