Binance Basis Oscillator illustrates the premium or discount between Binance spot vs perps.
This indicates whether speculators (i.e. traders on perps) are paying premium vs spot. If true then speculation is leading, indicating euphoria (at certain levels).
Conversely, spot leading perps (i.e. perps at a discount) shows extreme bearish conditions, where speculation is on the short side. Indicating times of despair.