Crypto
2 min read

Altseason

A period in the crypto market when altcoins outperform Bitcoin, often dramatically. Altseasons typically follow a Bitcoin rally as profits rotate into smaller-cap assets in search of higher returns.

What an altseason looks like

A canonical altseason has a recognizable shape:

  1. Bitcoin leads a rally, often pushing through prior cycle highs.
  2. Bitcoin dominance — Bitcoin's share of total crypto market cap — peaks and starts declining.
  3. Capital rotates first into Ethereum and other large-cap altcoins, which begin outperforming Bitcoin in dollar terms.
  4. The rotation moves down the cap stack into mid-caps and eventually into long-tail memecoins.
  5. Mainstream attention spikes, retail flows accelerate, and risk appetite peaks alongside the most speculative assets.
  6. Eventually the cycle exhausts, Bitcoin dominance bottoms, and altcoins correct violently.

Why it happens

Altcoins are higher beta than Bitcoin — they tend to amplify Bitcoin's moves both up and down. In a strong bull market, holders look for higher returns than Bitcoin can provide and rotate into riskier assets. In a downturn, the reverse happens: capital flees back to Bitcoin (the "safer" crypto) and out of crypto entirely. This dynamic produces the characteristic dominance cycle that traders watch.

The 2017 altseason ran from roughly mid-2017 through January 2018, with thousands of ICO-funded projects briefly rallying tens or hundreds of percent. The 2021 altseason had two phases: a DeFi-led rally in early 2021, then an NFT and gaming rally in summer and fall. The 2024–25 cycle was unusual in that memecoin and AI-agent tokens captured most of the speculative flow rather than the Layer 1 platforms that historically led.

How traders track it

Common heuristics:

  • Bitcoin dominance below a threshold (e.g., breaks 50% or 45%) — historically a signal that capital is rotating out of Bitcoin into the rest of the market.
  • The "Altcoin Season Index" — published by some sites, measuring whether 75% of top-50 altcoins have outperformed Bitcoin over a recent window.
  • ETH/BTC ratio — when Ethereum starts gaining on Bitcoin, it often precedes a broader altcoin rally.

None of these are reliable timing indicators. The shape of the cycle is recognizable in retrospect; the turning points are usually only obvious after the fact.

Reality

Altseasons are violent in both directions. The same dynamic that drives 5x and 10x rallies in mid-cap altcoins also drives 90% drawdowns when sentiment turns. Most altcoins from prior cycles never recovered their highs. The aggregate "altcoin index" performance over multiple cycles has historically lagged Bitcoin, even though individual altcoins occasionally produce outsized returns.