Altcoin season is a stretch of the crypto market when most large altcoins, meaning any cryptocurrency other than Bitcoin, outperform Bitcoin at the same time. The usual yardstick is the Altcoin Season Index. It calls an altcoin season when at least 75% of the largest altcoins have beaten Bitcoin's price performance over the previous 90 days. As of 25 October 2026 the market is not in altcoin season. BlockchainCenter's index reads 47, in its neutral band.
Where the market stands in October 2026
- 25 October 2026: BlockchainCenter's Altcoin Season Index reads 47, and the page states "It is not Altcoin Season!" Its last change of phase came on 2 September 2026, when the index moved from Bitcoin Season to Neutral.
- 12 October 2026: CoinMarketCap's version of the index reached 66, its highest level in a year. That reading was reported by Alice Liu, Head of Research at CoinMarketCap. In the same report, only 6 of 26 qualifying narrative categories rose over seven days. The index was rising while most sectors were falling.
- 25 October 2026: Bitcoin made up about 60.1% of total crypto market capitalisation and Ether about 10.6%, according to CoinGecko's global market data. Total market capitalisation stood at about $2.68 trillion.
So by October 2026 the index had climbed out of Bitcoin Season but never reached the 75 threshold. It then fell back during the second half of the month.
How the Altcoin Season Index works
Two widely used versions of the index follow the same logic but use different baskets.
| BlockchainCenter | CoinMarketCap | |
|---|---|---|
| Basket | Top 50 coins | Top 100 coins on CoinMarketCap |
| Window | Rolling 90 days | Rolling 90 days |
| Excluded | Stablecoins (such as Tether, DAI) and asset-backed tokens (such as WBTC, stETH) | Stablecoins and wrapped/asset-backed tokens |
| Altcoin Season | 75 or higher | 75% or more of the basket beat Bitcoin |
| Bitcoin Season | 25 or lower | 25% or fewer beat Bitcoin |
| Neutral | 26–74 | Between the two |
The calculation is simple. Take each coin's price change over 90 days and compare it with Bitcoin's change over the same period. The index is the share of coins that did better. If 40 of BlockchainCenter's 50 coins outperformed Bitcoin, the reading would be 80. CoinMarketCap says it counts Ethereum as part of the altcoin mix and refreshes the figure daily.
Because the baskets differ, the two indices can give different numbers on the same day. Compare readings only within one provider.
What the index cannot tell you
- It looks backwards. A 90-day window measures what has already happened. A reading of 78 could mean a season has just started, or that it peaked weeks ago and is fading.
- It measures breadth, not size. The index counts how many coins beat Bitcoin, not by how much. A narrow lead across many coins and a huge rally in a few can give very different readings.
- It only covers the largest coins. Thousands of smaller tokens sit outside both baskets.
- The thresholds are conventions. The 75 and 25 cut-offs are the index makers' definitions. They are not natural boundaries in the market.
Why altcoin seasons happen
The usual explanation is capital rotation. After a strong Bitcoin rally, some traders move gains into Ether and then into smaller, more volatile tokens in search of bigger returns. Bitcoin's share of total market value then falls. Bitcoin dominance is the main way to watch for this. A sustained decline means money is going into other assets faster than into Bitcoin.
This is a widely held market narrative, not a law. Dominance can also fall when Bitcoin drops faster than altcoins, and that is not a rally in anything. The October 2026 data shows this gap. The CoinMarketCap index hit a one-year high while most narrative sectors were down on the week.
What would the Altcoin Season Index read?
Enter how many coins in a basket beat Bitcoin over 90 days and the basket size to see the index reading and which band it falls in.
| Coins in the basket that beat Bitcoin's price change over 90 days | Coins in the index basket | Index reading (75 or higher = Altcoin Season, 25 or lower = Bitcoin Season) |
|---|---|---|
| 40 coins | 50 coins | 80 |
| 47 coins | 100 coins | 47 |
| 75 coins | 100 coins | 75 |
| 25 coins | 100 coins | 25 |
- Coin counts are your own inputs, not a live reading from any provider.
- The 75 and 25 cut-offs are the index makers' conventions; readings between them are the neutral band.
This shows the arithmetic only: it does not pick the basket, exclude stablecoins or wrapped tokens, measure how far coins beat Bitcoin, or forecast whether a season will start or last.
What past seasons looked like
CoinMarketCap Academy describes the last significant altcoin season as H1 2021. In that period altcoins outperformed Bitcoin "for almost 5 months straight", and the top 100 altcoins gained 174% while Bitcoin gained 2%. That comparison comes from one source, CoinMarketCap Academy, and has not been checked against a second data set here.
BlockchainCenter's own statistics suggest most seasons are short. It lists an average season length of a few weeks and long stretches without any season. The labels on those statistics are ambiguous on the live page, though, so the exact figures are not given here.
Signals people watch
None of these predict a season on its own. They show whether money is moving towards altcoins.
- Bitcoin dominance: a decline over several weeks, rather than a one-day move. Check whether it comes from altcoins rising or Bitcoin falling.
- Index direction within one provider: a climb from Bitcoin Season into the neutral band, as happened in September 2026, shows breadth improving but does not confirm a season.
- Sector breadth: whether gains spread across many categories or stay in one or two narratives.
- On-chain activity: transaction counts, active addresses and decentralised-exchange volume on networks other than Bitcoin, from public analytics dashboards.
Risks that grow during altcoin seasons
Fast-rising prices and heavy social-media promotion create good conditions for two common schemes:
- Pump-and-dump schemes: coordinated buying and paid promotion push a price up, and insiders sell into the buying wave.
- Rug pulls: a project team draws in money and then abandons the project or drains its liquidity.
Warning signs to check before buying any small token:
- An anonymous team with no verifiable track record.
- No smart-contract audit, or an audit by an unknown firm.
- Large token unlocks for the team or early investors coming soon.
- Liquidity on a decentralised exchange that is not locked.
- Marketing that promises returns.
Small-cap tokens can lose most of their value in hours when the market turns, and many never recover.
Key points
- Altcoin season means at least 75% of the largest altcoins beat Bitcoin over 90 days, on a specific provider's index.
- On 25 October 2026 it was not altcoin season. BlockchainCenter read 47, and CoinMarketCap's index had peaked at 66 on 12 October.
- The index confirms what has already happened. It does not forecast, and different providers' numbers are not interchangeable.
Limitations: index readings change daily, and the historical comparison rests on a single source. This article explains how a market indicator works and is not trading or investment advice.
