Altcoin spot volume just hit nearly four times Bitcoin's, the highest ratio since September 2025, and it is forcing a hard question. Is this early altseason or just fuel for a final BTC leg higher? The Altcoin Season Index rose to 62% in late September, with 72.5% of alts outperforming BTC in the week ending September 22, but it still sits below the 75 threshold that confirms a full altseason.
The tension is between the volume signal and the positioning. Glassnode notes that heavy altcoin participation has often coincided with local Bitcoin tops, and altcoin deposits to exchanges have climbed to levels last seen before the October 2025 peak. At the same time, altcoin futures open interest showed little growth, which differs from previous market tops that saw leveraged position build-ups. That mix suggests strong spot demand but not yet a blow-off top in derivatives.
For traders, the setup is about rotation and risk. Bitcoin dominance fell below 59% as capital rotated into alts, but BTC is still consolidating near 84,000 to 87,000 after its run from below 63,000 in August. The question is whether alts can sustain the bid without a decisive BTC breakout above 88,000 to 90,000, or whether this volume surge is a distribution signal into a local top.
Watch the Altcoin Season Index at 62 and then 75 for confirmation, and monitor BTC dominance at 59% for the next leg. A break below 58% dominance and a push above 75 on the index would signal a true altseason, while a bounce back above 60% dominance would suggest BTC is still anchoring liquidity. The next catalysts are the October monthly candle close and any follow-through in altcoin futures open interest to confirm whether this volume surge has leverage behind it.
