Act as a Chief Information Security Officer (CISO) for a major financial institution. Draft a detailed Incident Response Plan specifically tailored for a double-extortion ransomware attack. The plan must cover the six phases of incident response: Preparation, Identification, Containment, Eradication, Recovery, and Lessons Learned. Within the plan, include specific decision matrices for when to involve law enforcement, how to manage public relations to maintain stock price stability, and steps to ensure compliance with GDPR and financial regulations during the recovery phase.