Why this index exists
It answers one question in a second: is capital rotating into alts, or is Bitcoin still taking the lead? Use it as a regime map next to CI100 — not as a buy or sell signal.
If 75% or more of the large-cap coins beat Bitcoin over the last 90 days, it is altcoin season. Below 25 is Bitcoin season. Stablecoins and wrapped / asset-backed tokens are excluded.
Market regime
It is not altcoin season yet
38
Share of large alts beating Bitcoin over the last 90 days
Hover or drag across the chart. The dashed lines are the 25 and 75 thresholds.
Thu, 10 Sept 2026
38 / 100
Transition
| Season history, days | Altcoin season | Bitcoin season |
|---|---|---|
| Days since last season | 1692 | 9 |
| Average days between seasons | 90 | 30 |
| Longest stretch without a season | 1692 | 691 |
| Average season length | 22 | 13 |
| Longest season | 131 | 298 |
| Total days in season | 377 | 1048 |
It answers one question in a second: is capital rotating into alts, or is Bitcoin still taking the lead? Use it as a regime map next to CI100 — not as a buy or sell signal.
If 75% or more of the large-cap coins beat Bitcoin over the last 90 days, it is altcoin season. Below 25 is Bitcoin season. Stablecoins and wrapped / asset-backed tokens are excluded.
Above 75, alts are broadly outperforming. Below 25, Bitcoin is dominating. Between 25 and 75 the market is mixed — rotation has started, but it is not a full altseason yet.