BTC Altcoin Season Index: 33
What share of the 100 biggest other coins have beaten Bitcoin over the last 90 days. Above 75 people call it altcoin season; below 25, bitcoin season.
Out of the top 100 coins other than bitcoin, the percentage whose price rose more than bitcoin's over the past 90 days. It measures where money has been going, not whether anything went up.
For example, 82 means 82 of the 100 tracked coins beat bitcoin over three months — money has spread out into riskier coins, which in past cycles happened in the later stages of a rally. A reading of 15 means **only** 15 beat bitcoin, so money is concentrating in the safest crypto asset.
In a **falling** market a high reading only means the other coins fell less than bitcoin did.
In words: take the 100 biggest coins other than bitcoin, count how many had a bigger 90-day price change than bitcoin, and turn that count into a percentage. Above 75 is called altcoin season, **below** 25 bitcoin season.
The list of 100 coins moves with market value, so a coin that has just jumped can enter the list and push the reading up — the widely used version of this index behaves the same way. We began saving **one point per day** on 16 July 2026, so this line is short and grows by one point a day; there is no older history for it.
CoinGecko's free coin list (top 150 by market value) gives the ranking; DefiLlama gives each coin's 90-day price change. Stablecoins and wrapped or staked copies of other coins are removed first, then the top 100 that remain are compared.
CoinGecko top-100 ranking + DefiLlama 90-day returns · our daily record since 2026-07-16