IV rank places each name's 30-day at-the-money implied volatility inside its own 52-week range: 0 at the range low, 100 at the high. IV percentile is the share of the last 252 sessions that closed below today's reading. Both are measured from the median implied volatility of options within 5% of the money expiring in 20–60 days, on the session named above. Leveraged, inverse and volatility-linked ETPs are excluded — their implied volatility tracks the product's leverage, not a view on a company.