Lately I’ve been thinking about one question: why do some times the mainstream coins you hold don’t perform well, yet the whole market is going crazy upward? This actually involves a very critical metric—altcoin dominance.

Simply put, altcoin dominance is the market share percentage of all cryptocurrencies except Bitcoin. This indicator helps us judge whether funds are still chasing Bitcoin, or whether they’ve started flowing into other coins. When this ratio rises, it suggests that money is moving out of Bitcoin and into altcoins—often a signal that an altseason is coming.

You can understand this logic by looking at historical data. Before Ethereum appeared in 2017, Bitcoin had long dominated the market with more than 90% share. Then the ERC-20 standard and the ICO mechanism emerged, directly changing the rules of the game. Bitcoin’s dominance fell straight from 85% to 38%, as large amounts of capital poured into new projects. The DeFi and NFT boom of 2020–2021 happened again: Bitcoin’s dominance dropped from 70% to 40%. As of now (May 2026), Bitcoin’s market share is 57.27%, which is relatively balanced.

I’ve found that changes in altcoin dominance actually follow a very clear capital-rotation pattern. Typically, a full cycle has four stages: first, Bitcoin takes off on its own and dominance rises; then Bitcoin enters consolidation, and major coins such as Ethereum and Solana start to follow; next, capital continues flowing into coins with mid market caps; and only at the end comes a full-blown altcoin frenzy, where everything from small coins to micro coins surges.

To determine whether an altseason has truly arrived, I usually look for these signals. First, Bitcoin dominance continues to decline, especially when it breaks downward from the 60–70% range. Second, Bitcoin’s price moves sideways rather than still skyrocketing, because altcoins find it hard to attract attention while Bitcoin is in a crazy rally. Third, I use TOTAL2 and TOTAL3 to see whether the altcoin market’s trading volume and market cap are increasing.

However, there’s a pitfall you need to watch out for. Stablecoin growth can create false signals. USDT’s circulating market cap is now already $189.83B, and USDC has $77.36B. When the market turns fearful, funds tend to rush into stablecoins for safety—making altcoin dominance look like it’s rising, but in reality it reflects risk aversion, not a genuine altseason. So whenever I look at altcoin dominance, I always track stablecoin market-cap changes as a reverse indicator.

In practice, I use CoinGecko and TradingView to monitor these data. My focus is on the CRYPTOCAP:OTHERS.D indicator—this filters out the top ten coins so you can directly see the dominance of small and mid-cap coins. When this indicator is strong, it usually means risk-tolerant funds are entering the market.

Adjusting your position allocation based on these signals is the most practical approach. When Bitcoin dominance is high, you allocate heavily to Bitcoin; when you see dominance starting to weaken, you gradually rotate into Ethereum and other mainstream coins. Only when OTHERS.D begins to rise do you go all in on altcoins. At the same time, I build a risk-monitoring system: if both Bitcoin dominance and stablecoin dominance rise at the same time, that’s a risk-aversion signal; if both fall, that indicates funds are entering aggressively.

In the end, understanding altcoin dominance is about understanding the crypto market’s capital flows and sentiment. If you can catch the rhythm of capital rotation, you can find real opportunities in different stages. Under today’s market environment, institutional capital’s influence is increasing, and narrative-driven sector rotations happen more frequently—so this indicator’s reference value is actually higher now.