Altcoin Season Index

For each day, the index asks: what fraction of tracked altcoins beat Bitcoin's return over the previous 90 days? Above 75 is conventionally "altcoin season"; below 25 is "Bitcoin season."

Alt seasons are the euphoric late phase of bull markets — capital rotating down the risk curve — and they historically cluster just before cycle tops, which makes this as much a warning gauge as a celebration. Our universe is the ~27 tracked alts rather than the top-50 ITC uses, so exact values differ slightly; the regime signal is the same.