Santander has confirmed the appointment of Mahesh Aditya as chief executive of its UK division, effective from 1st March 2026. The current group chief risk officer will succeed Mike Regnier, who announced his departure from the position in October 2025.
The banking group simultaneously announced two further executive transitions. Pedro Castro e Almeida, presently chief executive of Santander Portugal, will assume Mahesh’s current role overseeing risk management at group level. Isabel Guerreiro, who has led digital operations across multiple markets, will take charge of the Portuguese business.
These appointments form part of a broader organisational restructuring that positions experienced internal candidates in critical roles across the group’s European operations. The timing aligns with Santander’s ongoing integration of TSB, following the acquisition announcement in July 2025.
UK leadership transition
Mahesh brings nearly nine years of experience within the Santander organisation to his new position. Since joining in 2017, he has occupied several senior positions, including chief executive of Santander Consumer USA and group chief risk officer. He has also served on the Santander UK board, providing him with direct exposure to the British market’s operational dynamics.
His immediate priority will involve overseeing the integration of TSB into Santander UK’s existing infrastructure. The acquisition, valued at approximately £1.4 billion, will expand the combined entity’s customer base and branch network across Britain. The transaction requires regulatory approval and remains subject to completion procedures.
Group risk management appointment
Castro e Almeida’s elevation to group chief risk officer draws on more than three decades of banking experience. He joined Santander in 1993 and has accumulated extensive knowledge of the organisation’s risk frameworks and operational practices across multiple jurisdictions.
During his tenure leading the Portuguese subsidiary since 2019, he transformed the operation into what the bank describes as the country’s most efficient and profitable banking institution. He also held responsibility for European regional operations between 2023 and 2025, giving him oversight of the group’s activities across the continent.
His background in both country-level management and regional coordination provides relevant experience for managing risk across Santander’s global operations, which span Europe, the Americas and other markets.
Portuguese market leadership
Guerreiro’s appointment as chief executive in Portugal marks a notable transition for the subsidiary. An engineer by training, she has concentrated her career on digital transformation and technology-led banking services. She previously served on the executive board in Portugal and held the position of group head of Digital for Europe.
Her experience in digital banking aligns with broader industry trends towards online and mobile service delivery. Portuguese banking customers have increasingly adopted digital channels for routine transactions, requiring banks to invest in technology infrastructure and user experience capabilities.
The appointment suggests Santander Portugal will maintain its focus on technological advancement whilst pursuing operational efficiency and market competitiveness.
Succession planning framework
The three appointees have collectively accumulated significant experience within Santander’s structure, understanding its culture, risk appetite and strategic direction. This continuity may facilitate smoother transitions compared with external appointments requiring adaptation periods.
“Mahesh and Isabel are proven and highly respected leaders who exemplify Santander’s culture, with a strong ambition for continuous improvement and a consistent track record of doing the right thing year after year for their teams, customers, shareholders and society. Pedro’s understanding of the group’s businesses and disciplined approach to risk makes him the right choice to lead the group’s risk function at this point. These changes demonstrate the depth of our bench of top management team and succession planning discipline, as well as our continued focus on delivering consistently our strategy and creating long-term value”. Ana Botín, Executive Chair, Banco Santander
The leadership changes occur as European banks navigate evolving regulatory requirements, shifting customer expectations and technological disruption across retail and commercial banking segments. Santander’s decision to promote from within reflects confidence in its existing talent pool and development programmes.