Mariana Seixas is a senior infrastructure lawyer and strategic business partner serving as Senior Legal Counsel at I Squared Capital, where she acts as Head of Legal for North America and Latin America. In this role, she advises investment and asset management teams across the full life cycle of complex infrastructure investments spanning energy, utilities, transport, digital, and social infrastructure, supporting one of the world’s leading independent infrastructure investors.

Mariana leads the legal structuring, diligence, and negotiation of a broad range of transactions, including control acquisitions, bolt-on acquisitions, credit investments, minority stakes, and venture capital investments, advising investment committees on material legal risks and deal terms. She is the primary legal adviser on asset management matters across the Americas, overseeing governance, regulatory compliance, disputes and investigations, refinancings, reorganisations, and exit transactions. Her work regularly involves coordinating multi-jurisdictional deal teams and external counsel across the United States, Canada, and Latin America, ensuring disciplined risk allocation and efficient execution aligned with investment strategy.

In addition to transactional leadership, Mariana plays a central role in portfolio oversight and governance, advising boards and senior management on fiduciary duties, related-party transactions, shareholder arrangements, and cross-border regulatory and litigation strategy. She has been instrumental in scaling I Squared Capital’s legal infrastructure in the Americas, developing centralised legal know-how, standardised M&A playbooks, and internal training programmes designed to institutionalise best practices and drive efficiency across teams.

Prior to joining I Squared Capital, Mariana spent over three years at SoftBank, where she rose to Director, Senior Counsel, representing the $8 billion SoftBank Latin America Funds and the SB Opportunity Fund, where she supervised 200 portfolio companies. There, she led legal execution for high-profile venture capital, growth equity, M&A, venture debt, SPAC, and public market transactions across Latin America, while also advising on fund governance, SEC filings, and portfolio company board matters. She was a key architect of SoftBank’s “GC 360” programme, delivering practical legal guidance to portfolio companies, and was a visible leader in diversity initiatives, including founding the Women in VC Series.

Mariana began her career at White & Case LLP, practising for nearly a decade in Miami and São Paulo, where she handled capital markets, project finance, bank finance, and M&A transactions throughout Latin America. She is trilingual (English, Portuguese, Spanish), admitted to practise in New York and Florida, and a graduate of the University of Virginia School of Law, where she served as an Executive Editor of the Virginia Law Review.

Her leadership and market standing have been consistently recognised, including selection to The Legal 500 GC Powerlist Miami 2024 and 2025 and the Attorney Intel Top 50 Attorneys in Miami 2023.