During the 2021 crypto bull market, many of the largest altcoins gained 300% to over 1,000% in just a few months, but not all at the same time. Knowing when capital begins rotating away from Bitcoin can make a huge difference. That’s where the Altcoin Season Index comes in, measuring whether the broader market is actually outperforming Bitcoin instead of simply following it.
What is the Altcoin Season index?
Altcoin season def: Altcoin Season is a period when most major crypto other than Bitcoin deliver stronger price gains than Bitcoin. It usually happens when investors begin moving profits from Bitcoin into altcoins, leading to broader market rallies.
Spotting an Altcoin Season isn’t as simple as watching one token surge. Markets often produce short-lived rallies that never spread across the broader crypto ecosystem. The Altcoin Season Index cuts through this noise by measuring whether most leading altcoins, not just a handful, are outperforming Bitcoin over a rolling 90-day period.
What the Altcoin Season Index Measures (and Doesn’t Measure)
What it measures
- The percentage of leading crypto that have outperformed Bitcoin over the previous 90 days.
- The breadth of market participation, i.e., whether altcoin strength is widespread or limited to a few assets.
- The direction of capital rotation between Bitcoin and the broader altcoin market.
What it doesn’t measure
- How much an altcoin has outperformed Bitcoin, only whether it has.
- Future price movements or whether an Altcoin Season will continue.
- Trading volume, liquidity, project fundamentals, or overall market sentiment.
How Does the Altcoin Season Index Works?
The Altcoin Season Index is usually in the form of a 90-day rolling score which measures the performance of the top 50 crypto (excluding stablecoins and wrapped tokens) against Bitcoin.
- Select the top 50 crypto: The index starts with the 50 largest crypto by market capitalization.
- Remove stablecoins and wrapped tokens: Assets like USDT, USDC, and WBTC are excluded because their prices either remain stable or mirror another crypto, making them unsuitable for performance comparisons.
- Compare each altcoin with Bitcoin: For every crypto, the index compares its 90-day percentage return with Bitcoin’s 90-day percentage return. If the altcoin’s return is higher than Bitcoin’s, it receives a “Yes” (or 1). If it performs the same or worse, it receives a “No” (or 0).
- Calculate the final score: The percentage of crypto that outperformed Bitcoin becomes the Altcoin Season Index. For example, if 38 out of 50 eligible crypto beat Bitcoin, the index score would be 76, indicating an Altcoin Season.
How to Read the Altcoin Index
The higher the Altcoin Season Index, the more widespread altcoin outperformance is compared to Bitcoin.
| Altcoin Season Index Score | Market Phase | What It Means | Typical Market Characteristics |
|---|---|---|---|
| 0–25 | Bitcoin Season | Fewer than 25% of the top crypto have outperformed Bitcoin over the last 90 days. Bitcoin is leading the market. | Capital remains concentrated in Bitcoin; Bitcoin dominance tends to rise, and most altcoins underperform. |
| 26–74 | Neutral Zone | Bitcoin and altcoins are sharing market leadership. Some sectors outperform, but there isn’t a broad market-wide trend. | Performance is driven by individual narratives (AI, Layer-1s, RWAs, memecoins, etc.) rather than a widespread altcoin rally; rotation is selective, not broad-based. |
| 75–100 | Altcoin Season | At least 75% of the top crypto have outperformed Bitcoin over the previous 90 days. | Capital rotates beyond Bitcoin into the broader crypto market; risk appetite increases and broad-based altcoin rallies become more common. |
Historical Example: The 2021 Altcoin Season
In early 2021, the Altcoin Season Index surged above 75 (peaking near 98 in April), confirming broad outperformance. Bitcoin dominance dropped sharply from ~60%+ toward 40-50% ranges as capital rotated. The ETH/BTC ratio strengthened significantly, leading major alts: large-caps delivered ~174% returns vs. BTC’s minimal 2% gains from February to May.
This mirrors potential setups today(July 2026): declining BTC dominance and rising ETH/BTC often signal rotation. History shows these metrics provide reliable evidence when aligned.
The Structural Liquidity Cascade: How the Index Moves
The Altcoin Season Index does not shift randomly; it documents a highly predictable, multi-phase liquidity transmission mechanism that has repeated across every major cryptographic market cycle.
- Phase 1 (Bitcoin Outperformance): Fresh capital enters the industry, primarily through institutional spot products or major exchange fiat on-ramps. Bitcoin leads the rally, breaking horizontal resistance zones and capturing global media coverage. The Altcoin Season Index hits rock bottom (below 15).
- Phase 2 (The Ethereum Pivot): As Bitcoin’s price begins to consolidate sideways at its local peak, institutional and retail traders look to maximize capital velocity. They rotate realized BTC profits directly into Ethereum (ETH), driving up the ETH/BTC valuation axis.
- Phase 3 (Large-Cap Aggregation): The liquidity injection flows down the market-cap ladder. Established Layer-1 foundations and major decentralized finance (DeFi) primitives experience massive volume inflows, pushing the index into the neutral zone.
- Phase 4 (The Full Alt Extension): Speculative euphoria peaks. Capital cascades into small-cap tokens and narrative-driven assets. The Altcoin Season Index hits print values above 80, signaling a highly overextended market layer that historically precedes a macro liquidity wash-out.
Indicators to Use Alongside the Altcoin Season Index
The Altcoin Season Index becomes more useful when combined with other market indicators that help explain where capital is flowing and whether the trend is being supported by broader market activity.
- Bitcoin Dominance (BTC.D)
Bitcoin Dominance measures Bitcoin’s share of the total crypto market capitalization. A sustained decline often suggests that investors are rotating capital from Bitcoin into altcoins, while a rising dominance indicates Bitcoin continues to attract a larger share of market liquidity. - ETH/BTC Ratio
The ETH/BTC ratio compares Ethereum’s performance directly against Bitcoin. Historically, Ethereum has often been one of the first major crypto to outperform Bitcoin before broader altcoin rallies emerge, making this ratio a useful early indicator of changing market leadership. - TOTAL3 Market Capitalization
TOTAL3 represents the combined market capitalization of all crypto excluding Bitcoin and Ethereum. Rising TOTAL3 values indicate that capital is spreading across the broader altcoin market rather than remaining concentrated in the two largest crypto. - Altcoin Trading Volume
Price movements are generally more reliable when supported by rising trading volume. Increasing volume across multiple altcoins suggests that a rally has broad market participation, whereas low-volume rallies may reflect short-lived speculation rather than sustained capital rotation. - Stablecoin Supply
Stablecoins are often viewed as deployable capital within the crypto ecosystem. Growth in stablecoin supply can indicate additional liquidity entering the market, increasing the potential for fresh investment into Bitcoin and, eventually, the broader altcoin market.
Final Thoughts
The Altcoin Season Index is a vital risk-mitigation tool which will allows you to avoid entering speculative positions prematurely when Bitcoin retains structural control, and flags when the altcoin market is becoming unsustainably overextended.
Integrate the index alongside real-time stablecoin issuance tracking and strict stop-loss boundaries to ensure your capital shifts are guided by empirical data rather than market hype.
Frequently Asked Questions
The Altcoin Season Index is a market-breadth metric that measures how many leading altcoins have outperformed Bitcoin over a rolling 90-day period. A higher score suggests that altcoin strength is becoming more widespread, while a lower score indicates that Bitcoin is still leading the market.
No indicator can confirm an Altcoin Season before it happens. Traders typically watch for a rising Altcoin Season Index, falling Bitcoin Dominance, a strengthening ETH/BTC ratio, and broader altcoin trading volume. Together, these signals may suggest that capital is beginning to rotate beyond Bitcoin.
It is not possible to predict with certainty whether a broad Altcoin Season will occur in 2026. Its timing will depend on factors such as Bitcoin’s performance, market liquidity, macroeconomic conditions, investor risk appetite, and whether capital spreads across a large number of altcoins.
A few altcoins rallying does not necessarily mean Altcoin Season has begun. Under the commonly used BlockchainCenter methodology, Altcoin Season is identified when at least 75% of eligible top crypto outperform Bitcoin over a rolling 90-day period. Broader volume and market participation can provide additional confirmation.
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