The greatest concern for a risk practitioner when an organization is adopting blockchain for a new financial system is the limited organizational knowledge of the underlying technology. Blockchain is a distributed ledger technology that enables secure and transparent transactions among multiple parties without the need for intermediaries or central authorities. Blockchain technology has many potential benefits for the financial sector, such as reducing costs, increasing efficiency, enhancing security, and improving trust. However, blockchain technology also poses many challenges and risks for the organization, such as technical complexity, interoperability issues, regulatory uncertainty, and cultural resistance. The limited organizational knowledge of the underlying technology is the greatest concern, because it affects the ability and readiness of the organization to adopt, implement, use, and maintain the blockchain system effectively and securely. The limited organizational knowledge could also result in poor decision-making, inadequate governance, insufficient training, and increased vulnerability to errors, fraud, or attacks. The other options are not as concerning as the limited organizational knowledge, although they may also pose some difficulties or limitations for the blockchain adoption. Lack of commercial software support, varying costs related to implementation and maintenance, and slow adoption of the technology across the financial industry are all factors that could affect the feasibility and sustainability of the blockchain system, but they do not directly affect the capability and maturity of the organization. References = 5