Historical Volatility (Parkinson) (20-Day)
Historical Volatility (Parkinson): The past volatility of the security over the selected time frame, calculated using the high and low prices on each trading day.
SPDR Bloomberg 3-12 Month T-Bill ETF (BILS) had 20-Day Historical Volatility (Parkinson) of 0.0015 for 2025-08-01.
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