Whenever people ask me if it's "alt season" yet, they're really asking about one number: Bitcoin dominance. It's Bitcoin's market cap as a percentage of the whole crypto market. At 55% dominance, Bitcoin is 55% of all crypto value. When that number rises, Bitcoin is beating altcoins as a group. When it falls, alts are winning. It's been a core lens on this market since altcoins first got big in 2017.
One thing worth flagging before you lean on it too hard. Dominance as it's usually calculated puts stablecoins in the denominator. Stablecoins have gone from basically nothing to well over $150 billion, so they drag dominance down arithmetically without representing anyone actually choosing alts over BTC. Some people use an "adjusted dominance" that strips out stablecoins and wrapped or pegged assets, and that gives you a cleaner read on the real BTC-versus-alt fight.
The shape the cycle keeps taking
Across several cycles now, dominance has traced a rough pattern. Early in a bull market, dominance rises. Bitcoin gets the first wave of new money, partly because it's the name everyone knows and partly because it's the most liquid way in for bigger players. That phase can run for months, and while it lasts, just holding BTC beats holding most alts.
Then Bitcoin's rally slows down, either from hitting technical resistance or because the pace of new money coming in levels off. The people who rode BTC up start hunting for bigger returns elsewhere. Capital rotates out of BTC into ETH first, then large-cap alts, then eventually mid and small caps. Dominance falls the whole time this rotation runs.
Late in the bull and into the correction it gets messier. During those parabolic blowoff tops in small caps, dominance can drop hard as speculative money floods the tiny tokens. When the correction lands, money exits small caps first, then mid caps, then large-cap alts, with some rotating back into BTC as the relative safe haven inside crypto. In bear markets dominance usually climbs, because alts fall further than Bitcoin does.
Spotting the rotation
The handoff from Bitcoin leadership to altcoin outperformance doesn't happen in a day. It plays out over weeks, and a few things help you see it starting. The main one is the ETH/BTC pair. When ETH/BTC puts in a bottom and starts trending up, money is moving out of Bitcoin and into the alt ecosystem. Ethereum is the gateway to DeFi, NFTs, and most alt activity, so ETH strength against BTC tends to come before any broad alt rally.
Total crypto market cap excluding Bitcoin is another one I watch. When that alt-only number starts making new highs while Bitcoin just consolidates, the rotation is on. It tells you whether aggregate money into alts is growing, no matter which specific tokens are catching the bid.
Funding rates on altcoin perps round it out. When BTC perp funding is cooling off but altcoin funding is heating up, speculative positioning is shifting from BTC to alts. That shift in appetite usually shows up before the bigger price move does. On Blockcircle I keep an eye on all three at once, since any one of them alone can fake you out.
Why it keeps repeating
A few forces drive this. Bitcoin is the gateway asset, so most new money enters through BTC because it's the most accessible, most liquid, and most institutionally accepted thing in crypto. That first inflow pushes dominance up.
Then there's return chasing. Once Bitcoin has run, people go looking for whatever hasn't moved yet. Alts that lagged BTC start to look cheap by comparison, and that demand fuels the rotation. It's the same risk-seeking behavior you see in every asset class.
And there's the narrative cycle. DeFi summer, the NFT boom, L2 season, AI tokens, one theme after another shows up and pulls capital into a specific corner. Those narratives are always about alts, never Bitcoin, because Bitcoin's story of digital gold and store of value barely changes. So when a fresh narrative grabs attention, money flows to the tokens tied to it and dominance slips.
Actually trading it
The simplest use is allocation. When BTC dominance is rising, lean toward BTC over alts. When it's falling, tilt toward alts. You don't have to nail the exact top or bottom of a dominance cycle, you just have to read the current trend right.
A more active version uses dominance as a filter for alt trades. When dominance is trending down, long alt setups have the wind at your back and better odds of working. When dominance is trending up, alt longs are fighting a headwind, and BTC longs or plain cash are usually the safer call.
The trap is overfitting to the past. Every cycle has its own quirks. The 2020 to 2021 run had DeFi and NFT narratives that didn't exist before. This cycle has ETF flows and real institutional Bitcoin buying that reshape the demand side. The broad Bitcoin-first-then-rotate pattern looks durable, but the timing, the size of the move, and which sectors win all change each time.
So treat dominance as one input, not a system. Stay flexible and update your read as new data comes in, and pair it with the ETH/BTC trend, altcoin volume breadth, and funding shifts so you have a fuller picture of where you actually are in the rotation.