Altcoin Season Index Slumps to 37 Amid Bitcoin Dominance Hold

The altcoin market continues to show limited expansion despite some recovery signals, with the Altcoin Season Index remaining in a neutral range. According to CoinMarketCap data as of May 15, the index stood at 37, unchanged from the previous day but showing deterioration compared to last week's 51 and last month's 47. The current index places it between the Bitcoin season (below 25) and Altcoin season (above 75), indicating that while some altcoins have rebounded recently, the market is more focused on narrowing the performance gap between Bitcoin and altcoins rather than broad expansion. The Altcoin Season Index calculates the percentage of top 100 altcoins (excluding stablecoins) with higher returns than Bitcoin over a 90-day period. Its annual high was 78 recorded on September 20, 2025, while its annual low was 14 set on December 19, 2025. Over the past 90 days, Bitcoin dominance has remained strong, with Bitcoin's market share at 58.8%, down slightly from last week's 59.2%. Meanwhile, other altcoins' share rose to 29.6% from 29.6% (unchanged), and Ethereum dominance increased to 11.5% from 11.3%. Bitcoin's market cap stood at approximately $1.5664 trillion with a 24-hour trading volume of $31.8128 billion, while the total altcoin market cap reached around $1.1052 trillion with a 24-hour trading volume of $58.3376 billion. As of May 15 at 11:30 AM, Bitcoin traded at $77,997, up 0.63% from the previous day, with a 90-day cumulative return of 20.96%.