Definition. The time series of model-interpolated 15-delta put implied volatility for the IBIT ETF, broken out by tenor.

Technical. Each data point represents the IV at target delta 15, obtained via interpolation across delta and maturity onto standard tenors. IBIT options follow US equity market hours (9:30 AM to 4:00 PM ET, Mon to Fri), so data appears flat outside trading sessions and on weekends and holidays.