What it measures
Share of the top 50 altcoins beating Bitcoin over 90 days — rotation measured, not predicted.
The Altcoin Season Index measures rotation, in one number: the share of the top 50 altcoins by market cap that have outperformed Bitcoin over the past 90 days — with stablecoins and wrapped assets removed, since they only track a peg or an underlying. At 20, altcoins are broadly losing to Bitcoin; at 80, the market’s risk appetite has rotated far out on the curve.
How to read it
This is a descriptive gauge, not a predictive one: it tells you what rotation has already happened, never what comes next. Readings above ~75 are the classic definition of an “altcoin season” — broad, indiscriminate outperformance that has historically appeared in the late, hottest phase of bull cycles. Readings below ~25 mean Bitcoin leads almost everything, typical of early cycles and risk-off phases. Read it together with Bitcoin dominance: the two describe the same rotation from opposite ends.
| 0 – 25 | Bitcoin season — BTC beats nearly every altcoin |
| 25 – 50 | Bitcoin leads — rotation has not broadened |
| 50 – 75 | Altcoins lead — appetite is moving out the risk curve |
| 75 – 100 | Altcoin season — broad outperformance, historically a late-cycle pattern |
Theses riding on this indicator
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Frequently asked questions
What counts as an “altcoin season”?
The common definition: at least 75 % of the top 50 altcoins outperforming Bitcoin over the trailing 90 days. It marks phases where capital rotates broadly and indiscriminately beyond Bitcoin — historically a late-cycle, high-risk-appetite pattern.
Does a high Altcoin Season Index predict anything?
No — and that is by design. The index describes rotation that has already happened. Historically, extreme readings clustered in late bull phases, but the index itself carries no forecast; treat it as a market-structure thermometer, like Bitcoin dominance read from the other side.
Why are stablecoins and wrapped tokens excluded?
Because they cannot “outperform” anything by construction: a stablecoin tracks a dollar and a wrapped or staked token tracks its underlying asset. Counting them would only dilute the measurement of genuine altcoin rotation.
How is this different from the Bitcoin Rainbow Chart?
The Altcoin Season Index measures something real and checkable — the share of coins beating Bitcoin over a defined window. The Rainbow Chart is a regression curve fitted to past prices; we rebuilt one and found that refitting it at different cut-offs moves the curve, and that a version fitted through 2017 was 2.7 times too low in 2021 and 44 per cent too high in 2026. It describes the past and forecasts nothing. Moonkelp deliberately carries the first kind of gauge and not the second.
Data & method
Collected automatically by the Moonkelp agent, validated against plausibility bands before anything is written. How the pipeline works →
We tested the chart people confuse this with: Bitcoin Rainbow Chart
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