Lorenzo Valente, Director of Research for Digital Assets at ARK Invest, expressed increased optimism regarding Bitcoin's ability to implement quantum defenses before the hypothetical Q Day. This outlook represents a shift from his position in mid-2025.
The assessment follows a white paper co-authored by ARK and Unchained, released on March 12, 2026. The research outlines five stages of quantum risk, arguing that the threat to Bitcoin will develop gradually rather than as a sudden event.
As of October 11, 2026, approximately 7.1 million BTC, or 35% of the circulating supply, are held in addresses with exposed public keys. These assets are theoretically vulnerable to Shor’s algorithm, which could potentially reverse-engineer private keys.
The research notes that many of these exposed coins are considered lost or can be migrated to quantum-resistant addresses. Furthermore, most Bitcoin addresses currently utilize hashed public keys, which are resilient to quantum attacks.
Current quantum hardware remains in the Noisy Intermediate-Scale Quantum era, lacking the capacity to compromise Bitcoin’s 256-bit elliptic-curve cryptography. Experts suggest that reaching such a threshold could take years or decades.
The Bitcoin ecosystem is actively exploring defensive measures, including the BIP-360 proposal. Future developments to monitor include the progress of this proposal and the adoption of new output types by wallets and exchanges.
