Altcoin Season Index Hits 100: What This Explosive Milestone Means for Q4 2025

Altcoin markets just flashed their strongest bullish signal in years—the Altcoin Season Index has officially maxed out at 100.

Breaking Down the Numbers

When the index hits triple digits, it signals overwhelming dominance by alternative cryptocurrencies over Bitcoin. Historical patterns suggest we're looking at potential parabolic moves across smaller-cap assets.

Q4 2025 Market Implications

Traders are repositioning portfolios faster than traditional finance can issue compliance memos. The timing couldn't be more strategic—entering Q4 with this momentum suggests altcoins might just outperform Bitcoin by margins that'll make Wall Street analysts question their career choices.

Market veterans are watching liquidity flows like hawks. Retail FOMO typically follows institutional moves within 2-3 weeks of such extreme readings. And let's be honest—watching traditional hedge funds scramble to understand decentralized governance tokens never gets old.

This isn't just technical indicator hype—it's market structure shifting in real-time. The index hitting 100 essentially screams that altcoin season isn't coming... it's already here.

Key Takeaways

What’s happening in the altcoin market?

TOTAL2 is hitting resistance, ETH.D is fading, and speculative froth in smaller altcoins is building.

How is BTC positioning affecting the market?

BTC.D is up 1.01% while ETH.D is down 2.86%, showing capital is rotating back into Bitcoin.

A week left into Q4, the market’s circling back to early September levels.

The Fear & Greed Index has reverted into the “fear” zone. Bitcoin [BTC] is just 3% above its $108k monthly open. Similarly, the total market cap (TOTAL) is hovering roughly 3% above its $3.70 trillion monthly base.

In short, the market has given back nearly 97% of its September gains. However, altcoins are taking the hardest hit, with TOTAL2 (ex-BTC market cap) down 4.43% (2x BTC’s loss) after getting rejected at key resistance.

Source: TradingView (TOTAL2)

However, there’s a notable divergence this time.

Unlike late Q2 and early Q3, when ETH dominance [ETH.D] nearly doubled to 15% and TOTAL2 spiked 30%, adding $510 billion into alts, ETH.D is trending the opposite way, showing rotation into altcoins is weak.

For context, since its mid-August peak at 15%, ETH.D has been in a steady downtrend, while TOTAL2 topped out at $1.73 trillion, meaning altcoins aren’t getting the usual boost from ETH, keeping capital locked elsewhere.

Altcoin market falters while BTC holds ground

Even with ETH.D on the sidelines, the Altcoin Season Index still popped. 

The index had been capped around 80, but on the 19th of September, the index broke out to 100. The trigger? Heavy capital rotated into alts after Aster [ASTER] launched, sending the index to a seven-year high.

The pump didn’t last, though. At press time, it’s back down to 69, just 10% above its September open. The bigger takeaway? This isn’t an “Altcoin Season” anymore, showing the recent capital FLOW was mostly speculative.

Source: Blockchain Center

In short, altcoin rotation is starting to fade. 

Backing this shift, bitcoin dominance [BTC.D] is up 1.01% this week (the only metric holding above September lows) while ETH.D is down 2.86%, signaling capital rotation back into BTC. 

Hence, with TOTAL2 capped, fading ETH/BTC rotation, and speculative froth building in smaller alts, the altcoin market looks primed for a deeper correction, making this a key divergence to watch for Q4 positioning.