ACH · IV Rank History

How these are measured. Implied volatility here is ACH's 30-day at-the-money IV: the implied volatility of the calls and puts struck nearest the share price, blended between the expirations on either side of 30 days so every reading covers the same horizon. It's the IV level options traders usually quote, and it doesn't jump when the nearest expiration rolls from a weekly to a monthly. The 7-day figure is the same measure a week out, so it reacts first to near-term events such as earnings.

52-week IV rank = (today's IV − 52-week low) ÷ (52-week high − 52-week low) × 100. IV percentile is the share of the past year's sessions that closed with lower IV than today. The 90-session IV rank applies the same rank formula to the last 90 sessions, so it reacts faster; there isn't a full year of history for ACH yet, so only the 90-session measures are shown.

A high reading means ACH options are expensive relative to their own recent history, which is common ahead of earnings or after a sharp move. It says nothing about which way the stock will go. The Vol Arb Screener ranks every tracked symbol by these measures.