Currently, Bitcoin accounts for approximately 60% of the value of the entire crypto market.
If this percentage dips below 60% for a sustained period of time, it could signal the arrival of "altcoin season."
During "altcoin season," smaller market cap altcoins far outpace the performance of Bitcoin, leading to outsized returns for investors.
For crypto investors, one of the most exciting times of the year is "altcoin season." That's when smaller market cap altcoins skyrocket in value, far outpacing the performance of Bitcoin (CRYPTO: BTC).
That's why inventors are constantly on the lookout for signals that altcoin season is nigh. Right now, a key indicator is flashing green. If history is any guide, some altcoins could be ready to go parabolic.
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That key indicator is known as the "Bitcoin Dominance" metric. It simply refers to the percentage of the crypto market's total market cap that Bitcoin accounts for. The higher the percentage, the more dominant Bitcoin is.
Right now, the market cap of Bitcoin is $1.7 trillion, while the total market cap of the crypto market is $2.85 trillion. Thus, the Bitcoin Dominance metric is sitting right below the key 60% threshold.
Image source: Getty Images.
Historically, the Bitcoin Dominance metric has been as high as 100%. That was in the early days of the crypto market, when Bitcoin was the only game in town. But over the past five years, this metric has ranged between 40% and 65%.

Market Cap BTC Dominance, % chart by TradingView.
For much of the past 12 months, though, the Bitcoin Dominance metric has been rangebound between 58% and 62%, making 60% the key level to watch.
If the metric dips below 60% for a sustained period, it will signal that altcoins are gaining ground at a much faster clip than Bitcoin, chipping away at Bitcoin's dominance. Think of it as crypto investors rotating out of Bitcoin and into better-performing altcoins.
With that in mind, it's possible to put together a potential shopping list of altcoins about to skyrocket in value.
Over the past 90 days, top performers include Zcash (CRYPTO: ZEC), Uniswap (CRYPTO: UNI), and Arbitrum (CRYPTO: ARB).All of these are up 200% or more. Other top performers include NEAR Protocol (CRYPTO: NEAR) and Venice (CRYPTO: VVV), both of which are up more than 100%.
If altcoin season is truly upon us, these could go parabolic. By way of comparison, Bitcoin is "only" up 40% over the past 90 days.
Just keep in mind: One indicator by itself does not make a trend. In other words, investors need to consider more than just the Bitcoin Dominance metric when determining whether it's altcoin season. There are entire mathematical models built around this.
My favorite go-to resource is from CoinMarketCap. The CMC Altcoin Season Index looks at the performance of the top 100 cryptocurrencies (as ranked by market cap) and asks a simple question: How many of these cryptos have outperformed Bitcoin over the past 90 days? If the answer is 75 or higher, it's altcoin season. Otherwise, it's still Bitcoin season.
Right now, the Altcoin Season Index is at 50, so roughly half of all cryptos are now outpacing Bitcoin. So don't pack your bags quite yet for altcoin season. There's still plenty of time to put smaller, lesser-known altcoins on your investment radar as we head into 2027.
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Dominic Basulto has positions in Bitcoin. The Motley Fool has positions in and recommends Bitcoin, NEAR Protocol, Uniswap Protocol Token, and Venice Token. The Motley Fool has a disclosure policy.