Altcoin season on the horizon? Altcoins flip Bitcoin on a key indicator

A shift in open interest unseen since late 2024

Is the long-awaited "altcoin season" finally underway? One indicator closely monitored by traders has certainly just shifted in favor of altcoins.

The aggregated open interest on altcoin perpetual contracts has overtaken that of Bitcoin (BTC) for the first time since December 2024, according to data from Coinalyze.

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In practical terms, open interest measures the total value of derivative contracts that remain open—neither closed nor liquidated. It rises when new positions are opened and falls when they are closed or liquidated. It is not, therefore, a directional indicator, but rather a gauge of the leverage present in the market.

Altcoin Open Interest is now higher than Bitcoin Open Interest for the first time since December 2024.

Do you guys remember what happened to alts after December 2024? pic.twitter.com/zsbZpdlbSF

— Ted (@TedPillows) September 5, 2026

Bitcoin still holds approximately $25 billion in aggregated open interest, including $23.9 billion in perpetuals alone, accounting for nearly 37% of the total tracked by Coinalyze. The rest, distributed across Ether, Solana, XRP, BNB, Zcash, and hundreds of smaller tokens, now exceeds the share held by BTC.

In the spot market, the momentum is moving in the same direction. The combined market capitalization of altcoins outside the top 10 has surpassed $200 billion and has grown by more than 10% since the start of the month. Meanwhile, the Bitcoin price is stabilizing around $79,500.

Zcash, the primary engine of the leverage surge

A significant portion of this expansion stems from a single asset: Zcash (ZEC). Open interest on ZEC futures hit a record of around $2.4 billion in early September, just as the token crossed the $1,000 threshold. This move triggered approximately $34 million in short position liquidations.

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ZEC has continued its rise since, with a price nearing $1,189 and a gain of more than 134% over 30 days. The rally has been fueled by the launch of the first Zcash spot ETF in the United States, converted from the Grayscale Zcash Trust and listed on the NYSE Arca under the ticker ZCSH.

A historical signal that shouldn't be over-interpreted

The precedent of December 2024 warrants caution. At the time, a similar shift was followed by sharp corrections across several mid-cap altcoins—a scenario traders have not forgotten.

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Analysis shared by specialized media outlets also suggests that a critical threshold is reached when total open interest hits approximately 4.42% of the total crypto market capitalization, a level at which cascading liquidations tend to accelerate.

The primary risk remains mechanical. Altcoin order books are thinner than those of Bitcoin. Consequently, a sudden move can trigger a much more violent cascade of liquidations.

The signals to watch in the coming days remain standard: funding rates, spot volumes, and the evolution of open interest. A simultaneous rise in leverage and funding, coupled with weakening spot demand, would paint a picture of a significantly more fragile market.

Sources: crypto.news, WuBlockchain, Bloomingbit