Altcoin season is back in focus as traders pivot from Bitcoin to higher-beta plays. According to the source, the Altcoin Season Index hit 82 out of 100 on September 19, 2025, indicating most altcoins are outperforming Bitcoin. Meanwhile, trading volumes in September reportedly favored altcoins over BTC and ETH.
Flows flip: Bitcoin ETF streak breaks
Momentum in Bitcoin softened midweek. Bitcoin ETFs saw $51 million in net outflows on September 17, 2025, ending a seven-day inflow streak. Fidelity’s FBTC and Grayscale’s GBTC led withdrawals, which the source links to the Federal Reserve’s cautious outlook. As a result, institutional sentiment appears to be cooling, at least in the short term.
However, the broader market rotated rather than stalled. With altcoin season strengthening, traders chased relative performance beyond Bitcoin. Therefore, liquidity shifted toward Layer-1s and DeFi-linked names.
Solana rallies toward record
Solana (SOL) traded near $246 on September 18, 2025, closing in on its all-time high of $294, per the source. The move coincided with a 165% jump in Solana’s DeFi Total Value Locked to $12.2 billion. Moreover, corporate adoption accelerated: Forward Industries purchased 6.8 million SOL for $1.58 billion, according to the source.
Key drivers cited include:
• Expanding DeFi activity and rising TVL
• Corporate balance-sheet exposure to SOL
• Market rotation during altcoin season
For context on market cycles and relative performance, see this overview of altcoins. However, prices remain volatile, and conditions can change quickly.
If you’re exploring stable-value rails during heightened volatility, our guide explains how stablecoins work and why traders use them between rotations.
