This is why 2021 was the last altcoin season!

The 2025 cycle has brought some notable differences to the market.

Previously, Bitcoin (BTC) often experienced strong price rallies after each halving, with the first four post-halving cycles driven by scarcity of supply and supply-demand imbalance. However, 2025 broke this pattern, as BTC ended the year with a 6% decline.

This divergence is also clearly evident in the altcoin market. The TOTAL3 index (market capitalization excluding BTC and ETH) has experienced its fourth consecutive year of decline compared to Bitcoin, marking the end of an “altcoin season” that has been gradually fading over the past four years.

Source: TradingView This clearly reflects the increasing influence of BTC on the entire market.

From a technical perspective, this is a reasonable development. Bitcoin’s dominance index (BTC.D) has maintained a continuous upward trend for four years, rising from around 40% in 2022 to over 60% in 2025. This means BTC’s market cap has increased by 100%, approximately $900 billion.

Notably, during the same period, the total market capitalization reached $1.11 trillion, indicating that nearly 80% of the new capital flowed into BTC, reinforcing its leading position. In this context, is the “altcoin season” still a promising phenomenon?

Looking back at the 2021 growth cycle – Key signals from the altcoin market

In retrospect, the 2021 cycle was truly a representative altcoin season.

On the 12-month chart, BTC’s market cap increased by 64% and for the first time surpassed the historic $1 trillion mark. However, the TOTAL3 (market cap excluding BTC and ETH) outperformed with a 541% increase.

As a result, the Altcoin Season Index peaked, signaling an explosive altcoin season with strong capital flows shifting into the broader altcoin market. However, since then, BTC has gradually taken control. So, what has really changed?

Source: TradingView (TOTAL3)The answer lies in the sharp increase in altcoin funding rates.

In other words, leveraged long positions are overloaded. While this may seem positive, in reality, it causes altcoins to fall into a cycle of high volatility, where even small fluctuations can trigger waves of liquidations.

Additionally, with the BTC.D index continuously rising, altcoins become more vulnerable to major market swings. In this context, the divergence between Bitcoin and altcoins is not accidental but rather evidence that 2021 might have been the “last true altcoin season.”