Bitcoin Dominance is the percentage of total crypto market cap held by Bitcoin. When BTC.D is rising, Bitcoin is capturing a larger share of the market – a sign of a “Bitcoin season” where BTC tends to outperform alts. Conversely, a falling BTC dominance (especially after a high peak) signals money rotating out of BTC into altcoins. Historically, ~60% BTC dominance has been a key pivot: above ~60–65% the market feels BTC-centric, but once dominance decisively breaks below ~60%, it has often triggered broad altcoin rallies.
The Altcoin Season Index (ASI) tracks how many top altcoins are outperforming Bitcoin over the last 90 days. If 75% of top coins (excluding stablecoins and pegged tokens) have outgained BTC in that period, it’s considered Altcoin Season; if only 25% or fewer are outperforming, it’s Bitcoin Season. In practice, an ASI reading above ~75 indicates a broad altcoin rally, whereas a low reading (sub-25) means BTC has beaten most alts (BTC-led market). For example, in mid-2025 the index was in the low-40s (well below the 75 alt-season threshold), confirming a BTC-dominated cycle at that time.
Beyond dominance and ASI, check Ethereum’s strength vs Bitcoin (ETH/BTC) and the total altcoin market cap (TOTAL2). When ETH/BTC is in an uptrend and breaking out, it signals investors rotating into ETH – often a leading indicator of a broader altcoin run.
Likewise, TOTAL2 (total market cap excluding BTC) making higher highs means the aggregate value of altcoins is climbing, confirming a broad-based bid for alts. Both ETH/BTC rising and TOTAL2 climbing together is a strong confirmation of an altcoin-friendly regime (capital flowing into the alt market). On the other hand, if ETH/BTC is stagnant or falling and the alt market cap is lagging, it suggests the market bias remains with Bitcoin or only a few large caps (no broad altseason yet).
In crypto, market leadership oscillates between Bitcoin and the altcoin pack. The term “Crypto Season Index” informally refers to tools that gauge these rotations – essentially distinguishing Bitcoin season vs Altcoin season. Rather than a single metric, it’s a concept based on a combination of indices and indicators that together tell us which side of the market (BTC or alts) is gaining momentum.
The Altcoin Season Index (ASI) measures whether altcoins are outperforming Bitcoin. It compares the returns of top cryptocurrencies (excluding BTC) against Bitcoin over set timeframes:
Trackers (e.g., BlockchainCenter, CoinMarketCap) use top 50–100 coins, excluding stablecoins, to avoid skew. A high ASI signals broad-based alt strength, while mid-range (40–60) suggests no clear leader.
In essence, ASI answers: “Is it altcoin season right now?” That said, this is often considered a lagging indicator, meaning by the time it flashes “Altcoin Season,” the rotation has often already begun.
There is no official “Bitcoin Season Index,” but traders infer it from the inverse of the Altcoin Season Index (ASI). When ASI falls below ~25, it signals a strong Bitcoin-led market—commonly referred to as Bitcoin season.
The main proxy for this is Bitcoin Dominance (BTC.D), which measures Bitcoin’s share of total crypto market cap. High dominance means Bitcoin is absorbing most capital, leaving less for altcoins. Historically, BTC.D above 60–65% aligns with periods when Bitcoin rallies or holds steady while alts lag—common in bear markets or the early stages of bull runs. For example, in mid-2025, BTC.D was around 65% while ASI hovered in the 40s, reflecting a BTC-driven market where Bitcoin neared new highs but many alts remained far below theirs.
A falling dominance, however, often marks the start of rotation. When BTC.D drops out of the 60s into the 50s (or lower), alts gain market share—an early clue that altseason may be underway. Past cycles show this tipping point clearly: in 2017, BTC.D plunged from ~85% to ~38% at the peak of altcoin mania, while in 2021, a break below 60% triggered a surge in alt gains.
In short, Bitcoin season is when Bitcoin dominates performance—its market share is high or rising, and most alts fail to keep up. Conceptually, it can be thought of as 100 minus the ASI, but in practice, traders rely on BTC Dominance and ASI together to judge the balance of power.
No single metric can define market cycles, which is why traders combine multiple signals to avoid false reads. The Altcoin Season Index (ASI) is a lagging indicator—by the time it shows 75+, altcoins have usually been outperforming for a while. Similarly, Bitcoin Dominance (BTC.D) can drop for reasons unrelated to alt strength, such as Bitcoin correcting while alts also fall.
To filter out fake outs, traders look for alignment across indicators. For instance, in September 2025 the ASI briefly spiked above 75 and alt volumes overtook Bitcoin’s, sparking claims that altseason had arrived. But BTC dominance was still high (upper-50s%), market sentiment remained muted, and many top alts were still down 80–90% from prior highs. That rally quickly faded, showing how reliance on one metric can mislead.
A stronger approach is multi-confirmation: combine BTC dominance trends, ASI readings, ETH/BTC strength, total market cap data, and sentiment checks. A genuine altcoin season usually shows them all moving in sync—BTC.D trending down, ASI high and sustained, ETH/BTC gaining, and alt markets broadly rising in price and volume. If only one of these flashes altseason while others remain neutral, caution is warranted.
In short, the real signal comes from confluence, not from a single index in isolation.
Here’s a five-step process to identify whether the market favors Bitcoin or altcoins—and how to trade accordingly.
Step 1 — Define the regime
Start by checking Bitcoin Dominance (BTC.D) on daily or weekly charts. If BTC.D is in an uptrend (higher highs, bullish moving average crossovers), Bitcoin is likely to outperform. If BTC.D breaks down below major averages or trendlines, it often signals the start of capital rotation into altcoins. For example, in July 2025 BTC dominance peaked near 65% before rolling over, coinciding with altcoin market cap bouncing higher. Recognizing whether BTC is “in charge” or faltering sets your trading bias.
Step 2 — Confirm breadth
Next, check whether altcoin outperformance is broad or narrow. The Altcoin Season Index (ASI) helps here. If ASI is low (20–30s), breadth is weak and BTC likely still leads. If ASI is rising toward 60+, more alts are outperforming, and momentum is shifting. An ASI above 75 signals full altseason, but the climb toward that level is often the key tell. In August 2025, ASI hit ~80, meaning 40 of the top 50 alts beat BTC—a classic breadth confirmation.
Step 3 — Cross-check signals
With BTC dominance weakening and ASI climbing, look for confluence across other indicators:
A real altseason usually shows all these factors moving together. If one lags (e.g., ETH/BTC stagnant), wait for confirmation.
Step 4 — Entry and exit rules
Step 5 — Manage risk
Crypto cycles are volatile, so discipline is key:
Traders use certain thresholds as guideposts, not hard rules. The Altcoin Season Index (ASI) is central: ASI above 75 signals a classic altseason, while below 25 favors Bitcoin. Values between 40–50 often act as an early tell, as seen in 2021 when ASI climbed from ~30 to 75 before alts surged.
Bitcoin Dominance (BTC.D) around 60% is another pivot. Above 60–65%, Bitcoin tends to lead; below 60% opens the door for alts. Other markers include 50% (often mid-altseason) or extremes like 70% resistance and 40% support. Though stablecoins now affect dominance, the psychological “over half vs under half” split remains powerful.
ETH/BTC serves as a bellwether. Breakouts above levels like 0.065–0.07, or reclaiming the 200-day moving average, often confirm alt strength. Likewise, rising Ethereum dominance signals leadership among large caps.
The Fear & Greed Index above 80 warns of euphoria and late-cycle risks, while sub-20 readings during falling dominance can mark contrarian buy zones. Similarly, high funding rates (>0.1% per 8h) or record open interest (OI)suggest crowded long positioning—conditions that often precede shakeouts. In Sept 2025, altcoin OI hit ~$39B, rivaling Bitcoin, just before a pullback.
False springs occur when one or two indicators flash green without broad confirmation: ASI spikes briefly then fades, BTC.D chops sideways, majors like ETH stay weak, or volume and sentiment remain muted. September 2025 was a textbook case: ASI hit ~80, but big alts stayed depressed and sentiment never flipped euphoric, and the rally soon fizzled.
Late-cycle warnings include parabolic charts, extreme leverage, Fear & Greed above 85–90, and frothy pumps in meme coins or low-quality tokens. When majors have already run and small caps start doing 10x overnight, the cycle is likely peaking.
The lesson: thresholds guide the map, but only confluence confirms the journey.
Traders often think in “seasons.” Here are three simplified playbooks for positioning:
1. Bitcoin Season Template
Bias: Heavy Bitcoin, light alt exposure.
Setup: BTC dominance rising, Altcoin Season Index (ASI) low, ETH/BTC weak.
Strategy: Allocate ~70% to BTC, 20–25% to ETH/top-10 alts, avoid small-caps. Focus on BTC technicals for entries and exits, trail stops closely, and cut any alt severely underperforming. Active traders may even short weak alts vs BTC. This phase continues until BTC.D stalls or ASI trends higher, hinting at rotation.
2. Early Alt Season Template
Bias: Rotate into large-caps, especially ETH.
Setup: BTC dominance peaks and rolls over, ASI climbs from 40→60, ETH/BTC breaks out.
Strategy: Shift to ~30–40% BTC and 60–70% alts, concentrated in ETH and other top-20 names like SOL, ADA, or XRP. Add exposure to strong narrative sectors (e.g. DeFi, Layer-2s). BTC remains a safety anchor, but the upside lies in majors. Risk management: set stops below key supports, cut laggards, and favor leaders. Example: In July 2025, ETH and SOL led double-digit rallies as BTC.D dropped, rewarding this allocation.
3. Full Alt Season Template
Bias: Broad exposure to mid-caps and select small-caps, with sector rotation.
Setup: ASI above 75, BTC.D in the 40–50% range, ETH/BTC strong but smaller alts outperforming.
Strategy: Diversify across baskets (Layer-1s, DeFi, Metaverse, Meme coins). Rotate profits as each sector peaks—e.g., from SOL/ETH to DeFi, then into gaming or memes. Keep some BTC/stables (10–20%) as a hedge. Risk management: use smaller positions in illiquid names, trail stops, and avoid chasing late movers. Example: In a classic alt frenzy, large-caps pump first, then mid-caps 3–5x, with meme coins marking the final blow-off.
In short, adapt allocation to the season: ride BTC strength, pivot to majors as dominance cracks, then broaden to alts while managing rotations and risk.
Tracking Crypto Season indicators is easier with the right dashboards and alerts. Here are the essentials.
Where to Track
Alerts to Set
Navigating Bitcoin vs Altcoin runs is clearer with a structured routine. Use this 5-point checklist each week (or when conditions shift):
1. Bitcoin Dominance Trend – Check BTC.D.
2. Altcoin Season Index (ASI) – Watch the index.
3. ETH/BTC + Alt Market Caps – Confirm leadership.
4. Sentiment & Leverage – Gauge market heat.
5. Cross-Indicator Agreement – Look for alignment.
This framework helps you adapt dynamically, tilting toward where momentum and capital are flowing,so you catch the season early, not after it’s obvious. Open an account with Mudrex, explore our curated CoinSets for diversified exposure to crypto.
How to predict altcoin season?
Watch for BTC dominance rolling over, Altcoin Season Index (ASI) rising toward/above 60–75, ETH/BTC breaking up, and TOTAL2 making higher highs—when 3+ of these align, rotation into alts is likely.
How to read the Altcoin Season Index?
It’s the % of top alts that outperformed BTC over ~90 days: >75 = Altcoin Season, <25 = Bitcoin Season, middle = mixed/transition; the Month view (30d) gives earlier, shorter-term signals.
Where does Bitcoin dominance need to be for altcoin season?
There’s no hard line, but sustained drops from the 60–65% area historically precede broad alt runs; deeper pushes below ~60% add confidence that rotation is underway.
Is ETH/BTC a good altcoin season signal?
Yes—ETH/BTC trending up or breaking out is one of the cleanest early tells that capital is rotating from BTC into large-cap alts, often before the smaller caps follow.
How long does altcoin season last?
It varies by cycle, typically weeks to a few months; it often starts with large caps (ETH, majors), then mid caps, and ends with small caps/memes before cooling off.
When is the next altcoin season?
No fixed date—wait for the checklist: BTC.D rolling over, ASI >60–75 and rising, ETH/BTC breakout, TOTAL2 strength, plus healthy volumes and non-extreme sentiment.
Is VWAP/SMA better than dominance for timing? (brief compare)
They answer different questions: VWAP/SMA help time trend entries on a single asset, while BTC dominance tells you where capital is flowing (BTC vs alts); use both—VWAP/SMA for entries, dominance for rotation bias.
Which indicators work best with the Crypto Season Index?
Pair ASI with BTC.D trend, ETH/BTC, TOTAL2/TOTAL3, volume breadth, funding rates/OI, and Fear & Greed; add MA/trendline breaks on BTC.D and ETH/BTC for cleaner confirmations.
Anush is a crypto researcher dedicated to making blockchain insights clear and accessible. A proud Solana maxi who still appreciates a good Layer 2 debate, he dives deep into market trends so others don’t have to (but really should). Passionate about simplifying crypto, he strives to make the space less intimidating and a lot more relatable, one report at a time.
