Altcoin Season Could Begin in September as Bitcoin’s Grip on Crypto Market Weakens: Coinbase Institutional

Altcoin season may be weeks away, according to Coinbase Institutional’s latest monthly outlook, which forecasts a shift in market leadership from bitcoin to alternative cryptocurrencies beginning in September.

Altcoin season refers to a market phase when cryptocurrencies other than bitcoin — often led by Ethereum's ETH, Solana's SOL, and other large-cap tokens — post significantly higher percentage gains than BTC over a sustained period.

The Aug. 14 report, authored by David Duong, Coinbase’s global head of research, identifies three main drivers: falling bitcoin market dominance, improving liquidity and growing investor willingness to rotate into higher-beta assets. Duong frames this as a cyclical transition, with capital moving down the risk curve as market confidence builds.

Bitcoin dominance — its share of total crypto market value — has shown signs of softening after peaking earlier this year. Coinbase argues that as this measure declines, capital historically flows into large-cap altcoins, and then into mid- and small-cap names. This rotation effect, they suggest, will become more pronounced in September.

Liquidity trends are also turning more favorable for altcoins. Coinbase notes tighter bid-ask spreads and deeper order books across major exchanges, making it easier for traders to enter and exit altcoin positions without incurring heavy slippage. Improved liquidity often encourages participation from larger players who might otherwise avoid less-traded tokens.

The third factor is sentiment. Duong writes that as macro conditions stabilize and volatility remains contained, investors are more likely to seek higher returns in riskier crypto assets. This environment could foster sustained inflows into the altcoin market, particularly if bitcoin’s price consolidates rather than surges to new highs.

Coinbase stops short of predicting which tokens will lead the charge but highlights the pattern from previous market cycles, where blue-chip altcoins outperformed first, followed by smaller-cap assets. The report cautions that while September may mark the start, the duration and magnitude of the move will depend on both market and macroeconomic conditions.

BTC is up 27.2% year-to-date but has trailed some major altcoins such as ETH (+37.9%) and XRP (+49%), while others like SOL (+1.67%), ADA (+8.96%) and DOGE (-27.5%) have lagged. Coinbase maintains that market conditions overall could favor a broader rotation into altcoins in the coming months.