Altcoins Gain Momentum Amid $2.77B Bitcoin ETF Inflows as BTC Rebounds From $82.5K

Altcoin momentum has picked up as Bitcoin ETF demand returns, with $2.77 billion in net inflows recorded across seven consecutive U.S. trading sessions from September 17 to September 27.

The surge in altcoin spot volume and participation is becoming more visible in market data. According to Glassnode, relative altcoin spot volume has risen to nearly four times Bitcoin's level on a seven-day basis, the highest relative level since September 2025.

This shift comes as Bitcoin trades within a tighter range, with investors reassessing risk across the crypto market. The increasing share of spot-market trading taking place outside of Bitcoin is reflected in Glassnode data, which shows similar spikes in relative altcoin demand around local Bitcoin price peaks during the 2024-2025 period.

The broader market rotation is also evident in the altcoin market cap, which has added more than $371 billion since June, representing a roughly 45% increase over that time. However, rising exchange deposits have increased, reaching levels not seen since October 2025.

While capital has been moving toward altcoins, Bitcoin continues to attract substantial investment through U.S. spot ETFs. Santiment reported $2.77 billion in net Bitcoin ETF inflows between September 17 and September 27, marking seven consecutive positive U.S. trading sessions.