Altcoin season, often shortened to alt season, is an informal name for a period when cryptocurrencies other than Bitcoin rise faster than Bitcoin does. It is a description of market behavior, not an official state with a start and end date. Nobody can reliably say in advance when one will begin, how long it will last or which coins will take part.
What Counts as an Altcoin
An altcoin is any cryptocurrency that is not Bitcoin. The term covers very different things: large networks such as Ethereum and Solana, DeFi tokens, exchange tokens and meme coins. Stablecoins are technically altcoins too, but they are built to hold a fixed value.
Bitcoin Dominance
The most common measure is Bitcoin dominance: Bitcoin's market value as a percentage of the total crypto market value. When altcoins outperform, dominance falls.
Dominance has to be read with care.
- It is a ratio: it can fall because altcoins are rising, or because Bitcoin is dropping faster than they are. The second case is not an alt season in any useful sense.
- Stablecoins distort it: a growing stablecoin supply raises total market cap and lowers Bitcoin's share without any altcoin gaining value.
- New tokens inflate the total: thousands of new coins are launched every year, and their market caps are added to the total even if few people can sell at those prices.
- There is no magic level: no specific dominance number has reliably marked the start of altcoin outperformance.
Some websites publish an "altcoin season index", usually based on what share of large coins beat Bitcoin over the previous 90 days. These describe what has already happened. They do not forecast.
Why Rotation Happens
The usual explanation is a rotation of capital. In past cycles Bitcoin tended to move first. Holders with gains then moved part of their money into large altcoins in search of bigger percentage returns, and from there into smaller and riskier coins.
Smaller coins move more because their markets are thinner. A modest amount of buying can move the price a lot. The same thinness works in reverse when buyers leave.
This sequence is an observation about a small number of past cycles. It is not a rule, and the market's structure has changed. Spot Bitcoin exchange-traded funds began trading in the United States in January 2024. Money that buys Bitcoin through a fund in a brokerage account cannot rotate into small on-chain tokens the way money on a crypto exchange can. The number of tokens has also grown enormously, so the same capital is spread across far more assets.
Past Altcoin Seasons
Two periods are usually cited.
In 2017 and early 2018, a wave of initial coin offerings on Ethereum drove very large gains. Ether rose from around $10 at the start of 2017 to more than $1,300 in January 2018. Bitcoin dominance, which had been above 85% in early 2017, fell below 40%. In the bear market that followed, most ICO tokens lost the large majority of their value, and many disappeared.
In 2021, altcoins rallied strongly in the spring, driven by DeFi, NFTs and meme coins such as Dogecoin. A second run in the autumn took Solana and Avalanche to record highs. Bitcoin peaked near $69,000 in November 2021. In 2022, most altcoins fell much further than Bitcoin did.
Signs People Watch
- Falling Bitcoin dominance: while total market value is rising.
- ETH/BTC ratio: Ether gaining against Bitcoin has often come before wider altcoin strength.
- Breadth: many coins rising together, not only one or two.
- Volume: rising trading volume in altcoin pairs.
- Retail attention: search interest and social media activity around specific themes.
Each of these has given false signals. They are context, not triggers.
The Risks
Altcoins fall harder than Bitcoin in downturns. Declines of 70% to 90% from the peak have been common for altcoins in past bear markets, and many never recovered.
Liquidity can disappear quickly. A small coin that was easy to buy on the way up may have few buyers on the way down, so the price you see is not the price you get.
Hype also attracts fraud. The CFTC's advisory on virtual currency trading warns about the risks of speculative trading in these markets. The SEC's investor.gov crypto asset resources cover common scams, including pump and dump schemes, which become more frequent when prices are rising and attention is high.
Common Mistakes
- Buying after the move: by the time a theme is everywhere on social media, much of the rise has often already happened.
- Treating the pattern as a schedule: past cycles do not guarantee that the next one will follow the same order, or happen at all.
- Ignoring token supply: a coin with large scheduled releases of new tokens faces steady selling pressure regardless of the market mood.
- Concentration: putting a large share of savings into a few small coins.
- No exit plan: deciding in advance what you would do in both directions is easier than deciding during a sharp move.
- Forgetting tax: in many countries, swapping one coin for another is a taxable event.
Nothing in this article is financial advice.
Key Points
- Altcoin season is an informal label, not an official signal.
- Bitcoin dominance is the main measure, and it can mislead.
- The two clearest past examples were 2017 to early 2018 and 2021.
- Both were followed by deep losses in most altcoins.
- No indicator has timed it reliably.
Track on CoinMarketGuy
The homepage shows the Fear and Greed reading along with total market cap and volume, which give a quick sense of market mood. The trending page lists the most searched coins. Compare the Bitcoin price page with the Ethereum price page to see which of the two has been stronger.