Understanding Bitcoin Dominance and Alt Season

You are watching cryptocurrency charts and Bitcoin has just reached a new high. You check your portfolio, expecting your other tokens to be up as well, but they have barely moved. A few weeks later, Bitcoin stalls, then some of those smaller tokens start rising very quickly.

You may be seeing a common pattern in crypto markets. To understand why this can happen, it helps to understand two ideas: Bitcoin dominance and alt season.

What is Bitcoin dominance?

Bitcoin dominance is a way of measuring Bitcoin's share of the overall cryptocurrency market. It is calculated by taking the market capitalisation of Bitcoin and dividing it by the total market capitalisation of all cryptocurrencies combined.

You can think of the entire cryptocurrency market as a shared pie. Bitcoin dominance measures the size of the slice that belongs to Bitcoin. If the overall pie grows, but Bitcoin's slice grows faster than the rest, then its dominance increases.

This metric is strongly influenced by market sentiment. When investors are nervous, or when a new market cycle is starting, many treat Bitcoin as a relative safe haven compared with other cryptoassets, even though it is still very risky and highly volatile. This move towards Bitcoin can cause its dominance to rise.

When investors feel more optimistic and are willing to take on more risk, they may move into alternative coins. This extra demand for altcoins can then cause Bitcoin dominance to fall, but it also increases the risk of sharp losses if sentiment suddenly reverses.

What is an alt season?

Alt season is short for alternative cryptocurrency season. It refers to a phase in the market cycle where alternative coins, often called altcoins, see a surge in trading volume, market interest, and price performance, and where they significantly outperform Bitcoin for a period of time.

Some traders use a simple guideline to decide if an alt season is underway. Often called the 75 per cent rule, it suggests an alt season is happening if 75 per cent of the top 50 cryptocurrencies perform better than Bitcoin over a 90‑day period. This is only a rule of thumb and not a guarantee of future outcomes.

During these periods, it is possible to see frequent double‑digit daily percentage moves across unrelated assets, driven mainly by speculation and market hype. While this can feel exciting, it also means risk is very high and prices can reverse violently with little warning.

How it works in practice

Crypto markets often move in cycles of capital rotation. Money can move from larger, more established assets into smaller, riskier ones. A typical pattern might look like this, although markets do not always follow the same script:

• Bitcoin takes the lead: Institutional and retail capital flows into Bitcoin first, which can drive its price and dominance higher. Bitcoin itself is very volatile and carries a high risk of loss, even at this stage.
• Consolidation begins: Bitcoin reaches a local peak and starts to trade sideways as some investors take profits or reduce risk. Prices can still move sharply both up and down.
• Capital rotates: Some investors looking for potentially higher returns move part of their profits from Bitcoin into larger altcoins such as Ethereum or Solana. These assets are generally more volatile than Bitcoin, so the risk of large losses increases.
• The season peaks: Money flows further into mid‑cap and low‑cap tokens. Prices can rise very quickly across the market, but these assets are often the most illiquid and speculative, so they can fall just as fast or faster.

There have been versions of this pattern several times in the past. In January 2018, after a strong run in Bitcoin, its dominance fell from over 60 per cent to roughly 32 per cent as many altcoins briefly reached all‑time highs. Soon after, many of those altcoins fell by more than 90 per cent from their peaks and took years to recover, if they recovered at all.

In 2020, the market experienced a sector‑focused phase often called DeFi Summer, where many decentralised finance tokens rose rapidly while Bitcoin was quieter. Again, much of this value later reversed, which caused large losses for late entrants.

Recent cycles have been more fragmented. The arrival of institutional capital through products such as spot ETFs / ETNs has meant that some larger investors mainly stick to major assets like Bitcoin and Ethereum. Instead of every coin rising together, now there is often smaller mini‑seasons, where specific sectors such as artificial intelligence tokens or meme coins move independently. These moves are usually very speculative and very risky.

Risks and how to stay safe

Although alt seasons can offer the potential for high returns, they are extremely volatile.

One major warning sign is extreme market euphoria. When sentiment indicators show high greed, and lesser‑known tokens are rising rapidly without any meaningful news or development progress, the market may be overheating. Alt seasons are usually short‑lived and very hard to time. When the momentum fades and liquidity dries up, altcoins can fall 90 per cent or more against Bitcoin and against fiat currencies such as GBP, and some may never recover.

Holding any alternative coin does not guarantee profit, even during an alt season. In recent years, projects with strong usage and active communities have started to separate from older networks with few or no real users. Many tokens have limited utility, and some may fail completely.

Before buying any token, it is important to:

• Research the underlying technology and what the project is trying to achieve.
• Look for evidence of real user adoption and active development.
• Understand how the token is issued, who controls the supply, and any planned unlocks.
• Be cautious of social media hype, celebrity endorsements, and promises of easy or guaranteed returns.

Never rely on a single metric such as Bitcoin dominance or an alt season indicator to make investment decisions. Consider your wider financial situation, your risk tolerance, and whether you can afford to lose the full amount you plan to invest.

Why Bitcoin dominance and alt season matter

If you zoom out, the relationship between Bitcoin dominance and alt season can give a rough guide to market sentiment and risk appetite in the wider crypto market. It is not a crystal ball, but it can provide useful context.

Tracking these metrics can help investors understand where capital is currently focused. When money rotates out of Bitcoin into other networks, it can increase funding for new technologies, decentralised applications, and blockchain infrastructure. This can sometimes support innovation, but it can also fuel bubbles in low‑quality projects.

By understanding these patterns, you may be better able to recognise when the market looks more cautious, and when it looks more speculative. This context can support more informed decisions about if, when, and how you choose to get exposure to digital assets, or whether you decide to avoid them altogether.

Remember that past performance is not a reliable indicator of future results. Market cycles can change, and there is no guarantee that previous patterns in Bitcoin dominance or alt seasons will repeat.