ARK Invest Quantifies Bitcoin’s Quantum Risk

Bitcoin

A new white paper from Cathie Wood’s firm forces the crypto industry to confront a risk it has long treated as distant. The debate has barely begun.

Key Takeaways

ARK Invest’s white paper identifies ~6.9 million BTC (roughly 35% of supply) as theoretically vulnerable to future quantum attacks due to exposed public keys.
The threat is classified as a long-term engineering problem, not an imminent crisis – most experts place “Q-Day” in the mid-2030s at the earliest.
BIP-360 is the Bitcoin community’s current proposed fix, but implementing it requires network-wide consensus – a process that could take years.
Capital rotation into AI, not quantum fear, is the more immediate driver behind Bitcoin’s 2026 price weakness, according to developer Matt Corallo.

For years, quantum computing has hovered over the cryptocurrency space as a vague, theoretical threat – something to worry about eventually. ARK Invest just made it harder to look away.

In a jointly published white paper with Bitcoin-native firm Unchained, shared by Benzinga, ARK quantified what was previously left abstract: approximately 6.9 million Bitcoin, or roughly 34.6% of the total circulating supply, could be vulnerable to a sufficiently powerful quantum computer. The report, titled Bitcoin and Quantum Computing, has drawn immediate attention from developers, analysts, and institutional investors – not because it signals imminent danger, but because it maps the exposure with a precision the industry hasn’t seen before.

What Makes These Coins Vulnerable

The core issue involves public keys. For most Bitcoin held today, the public key remains hidden behind a cryptographic hash until the moment of spending. A quantum computer capable of running Shor’s algorithm at scale could theoretically derive a private key from an exposed public key – but only if it can see the public key in the first place.

ARK identifies three categories where that condition is already met. The largest group involves address reuse: roughly 5 million BTC sits in wallets where the public key was exposed the moment funds were sent out and then received back into the same address. Early “Pay-to-Public-Key” (P2PK) addresses – including those associated with Satoshi Nakamoto – account for another 1.7 million BTC, where the public key has been permanently visible on-chain since the network’s earliest days. A smaller tranche, approximately 200,000 BTC, involves specific Taproot outputs that expose keys through what is called the “key path” spending mechanism.

None of this means these coins can be stolen today. It means they would be the first targets if quantum hardware ever reaches the necessary threshold.

What That Threshold Looks Like

ARK’s own estimate suggests breaking a single Bitcoin public key would require approximately 2,330 logical qubits and billions of quantum gate operations. That hardware does not exist. Current quantum systems remain far below the error-correction capabilities needed to execute an attack of that scale reliably.

The report treats “Q-Day” – the hypothetical moment when encryption breaks – as a mid-2030s scenario at the earliest. Ethereum co-founder Vitalik Buterin, writing in late 2025 and early 2026, placed the probability of a meaningful quantum breakthrough before 2030 at around 20%, while publicly pushing for “quantum readiness” roadmaps across major blockchain networks.

The more pressing data point may come from the hardware side. Chicago-based PsiQuantum is reported to be on track to complete a facility housing one million physical qubits by 2027. Whether that translates to cryptographically relevant logical qubits remains an open question – but the trajectory is no longer purely speculative.

BIP-360 and the Governance Problem

The Bitcoin developer community has not ignored the risk. Coinciding with the ARK white paper’s release is the formal introduction of BIP-360, a Bitcoin Improvement Proposal that would restructure how Taproot transactions are handled. Specifically, it proposes a “Pay-to-Merkle-Root” (P2MR) model that eliminates the key path spending option entirely, forcing transactions through a script path and keeping elliptic curve public keys off-chain.

Longer term, ARK suggests Bitcoin will need to adopt post-quantum cryptographic signature schemes – either ML-DSA, which is lattice-based, or SLH-DSA, a hash-based alternative – both designed to remain secure against quantum-scale computation.

The technical roadmap, however, runs headlong into Bitcoin’s governance structure. Unlike a corporate software product or even Ethereum’s more developer-steerable architecture, Bitcoin upgrades require broad consensus across miners, node operators, and the developer community. Analysts familiar with the process warn that even if the cryptographic solution is agreed upon, coordinating an actual “Quantum Soft Fork” deployment could take the better part of a decade.

Three Schools of Thought on What Happens Next

Reactions to the ARK report have split along predictable lines, though each position has some analytical substance behind it.

The bullish camp, represented most visibly by Bitcoin advocate Michael Saylor, argues that quantum computing will ultimately strengthen Bitcoin rather than destroy it. In this view, the network upgrades, active users migrate to quantum-resistant addresses, and the “vulnerable” coins – many of which belong to lost wallets or Satoshi’s long-dormant holdings – effectively get frozen out of circulation. The result would be a smaller, scarcer supply with stronger cryptographic guarantees.

Institutional skeptics offer a different reading. Some analysts have pointed to Ethereum’s comparatively faster development cycle on post-quantum cryptography as a potential inflection point. If Ethereum achieves quantum hardening before Bitcoin, the argument goes, institutional capital – already attuned to security risk after a decade of compliance scrutiny – could rotate toward the “safer” asset, accelerating what some call a “flippening” scenario.

A third camp, common among developers, dismisses the Bitcoin-specific framing altogether. Their argument: if a quantum computer can break Bitcoin’s elliptic curve cryptography, it can break the encryption underlying global banking infrastructure, government communications, and critical industrial systems. At that point, the fate of any individual blockchain becomes secondary to far larger systemic failures. The “meteor argument,” as it’s sometimes called, treats Q-Day not as a crypto problem but a civilizational one.

Corallo’s Warning: Quantum Is Becoming a Convenient Scapegoat

Amid the renewed debate, Bitcoin developer Matt Corallo offered a sharper critique in comments made on the Unchained podcast in February 2026. His concern is less about the quantum threat itself and more about how it is being used to explain market behavior it has nothing to do with.

Corallo’s logic is pointed: if investors were genuinely pricing in a near-term quantum crisis, Ethereum – with its more flexible upgrade path and more active research agenda on post-quantum cryptography – should be outperforming Bitcoin. It isn’t. Both assets have fallen substantially from their 2025 peaks, which suggests something else is driving the pressure.

That something else, in Corallo’s assessment, is capital rotation into artificial intelligence. Bitcoin mining and AI data infrastructure are now direct competitors for the same scarce resources – specialized chips, power contracts, and physical space. As institutional capital tilts toward AI infrastructure investment, it is exiting crypto positions across the board. Quantum computing, in this reading, is being blamed for a macro shift it didn’t cause.

Corallo’s own timeline for a credible quantum threat sits at 10 to 20 years or beyond. He is not dismissing the risk – he is dismissing the panic.

What to Watch

The immediate near-term marker is BIP-360’s progress through the Bitcoin developer and miner consensus process. Its adoption – or rejection – will signal how seriously the network’s stakeholders are treating the long-range risk. PsiQuantum’s 2027 facility completion will also serve as a hardware benchmark: the gap between physical qubits and cryptographically relevant logical qubits is where the real timeline uncertainty lives.

For now, ARK’s white paper has done what it set out to do – replaced vague concern with specific numbers. Whether the Bitcoin ecosystem acts on those numbers with the speed the timeline may eventually demand is a governance question, not a technical one. And historically, governance is where Bitcoin moves slowest.

The information provided in this article is for educational purposes only and does not constitute financial, investment, or trading advice. Coindoo.com does not endorse or recommend any specific investment strategy or cryptocurrency. Always conduct your own research and consult with a licensed financial advisor before making any investment decisions.

Author

Alex is an experienced financial journalist and cryptocurrency enthusiast. With over 8 years of experience covering the crypto, blockchain, and fintech industries, he is well-versed in the complex and ever-evolving world of digital assets. His insightful and thought-provoking articles provide readers with a clear picture of the latest developments and trends in the market. His approach allows him to break down complex ideas into accessible and in-depth content. Follow his publications to stay up to date with the most important trends and topics.