TLDR
- Ark Invest estimates 6.9M BTC worth about $483B could face future quantum risks.
- Around 1.7M BTC in old P2PK addresses may remain permanently exposed.
- About 65.4% of Bitcoin supply sits in non-quantum-vulnerable addresses.
- New proposal BIP-360 aims to add quantum-resistant address structures.
A new report from Ark Invest states that a large share of Bitcoin could face future risks from quantum computing. The study estimates that about 6.9 million BTC may be vulnerable if current cryptography becomes breakable.
At a median Bitcoin price of $70,000, the amount equals about $483 billion. The research was conducted jointly by Ark Invest and Unchained. The report states that older address formats and address reuse create most of the exposure.
The analysis also shows that about 65.4% of Bitcoin’s supply remains in addresses that are currently safe from such risks.
Large Share of Bitcoin Could Be Exposed to Future Quantum Attacks
Ark Invest and Unchained estimate that about 34.6% of Bitcoin’s supply could face long-term risk from quantum computing. This portion equals around 6.9 million BTC.
The risk is tied to the Elliptic Curve Digital Signature Algorithm. Bitcoin uses this system to secure ownership and authorize transactions.
Quantum computers could run Shor’s algorithm to derive private keys from public keys. If that happens, attackers could move funds from vulnerable addresses.
ARK Invest and Unchained released a joint white paper showing that about 34.6% of the Bitcoin supply remains exposed to long-term risks from potential breakthroughs in quantum computing, while 65.4% of the supply is currently considered relatively secure. In addition, the… pic.twitter.com/Ogo3rkzUUA
— Wu Blockchain (@WuBlockchain) March 12, 2026
The report divides the vulnerable supply into different groups. Around 5 million BTC, or about 25%, are exposed due to address reuse. These coins can still move to newer and safer address formats.
Another 200,000 BTC sits in Taproot addresses. These coins are also considered migratable to improved structures if new standards appear.
Ark Invest states that “about one-third of the Bitcoin supply could be exposed in a worst-case quantum scenario.”
Old Wallet Types Hold the Most Exposed Bitcoin
The study shows that early Bitcoin address types carry the highest exposure. Around 1.7 million BTC are stored in old Pay-to-Public-Key addresses.
In this format, the public key appears directly on the blockchain. This means a future quantum computer could target those keys more easily.
Many of these coins date back to Bitcoin’s early years. Analysts believe a large share may already be lost because the private keys are missing.
If those keys remain lost, the coins cannot move to new address types. As a result, they would remain exposed if quantum computing advances far enough.
Newer formats, such as Pay-to-Public-Key-Hash and Taproot, hide the public key until a transaction occurs. This design lowers the chance of direct quantum attacks.
Because of this structure, most modern wallets are considered safer for now.
Bitcoin Developers Prepare Quantum Resistant Upgrades
The report states that current quantum technology does not create an immediate risk. Modern quantum systems remain in what researchers call the NISQ stage.
Existing machines operate with fewer than 100 logical qubits and high error rates. Breaking Bitcoin’s cryptography would likely need thousands of stable logical qubits.
Researchers also estimate that billions of quantum operations would be required to break the secp256k1 curve used by Bitcoin.
The study suggests that such capability may appear around the mid-2030s. This timeline gives the network time to prepare and upgrade.
Developers are already discussing solutions. One proposal, known as BIP-360, introduces quantum-resistant address structures.
The proposal aims to work with Taproot while allowing migration to post-quantum cryptography. If adopted, users could move funds from vulnerable addresses before quantum systems become powerful enough.
