State Street Corporation (NYSE: STT) announced it will provide comprehensive servicing for Thornburg Investment Management's new ETF share classes, expanding a partnership that began in 1987.

Under the expanded arrangement, State Street will deliver end-to-end ETF services including custody, accounting, basket creation, order management, settlement, transfer agency, and reporting for Thornburg's new share classes. The announcement represents the second active ETF share-class servicing mandate in the United States with State Street as provider.

Thornburg, a privately owned global investment firm headquartered in Santa Fe, New Mexico, manages approximately $57 billion in client assets as of March 31, 2026. The firm operates across equity, fixed income, multi-asset, and alternative investment strategies.

The ETF share classes represent an extension of Thornburg's existing ETF platform, which launched in January 2025 with State Street's support. State Street currently provides full-service support across Thornburg's product lineup, including mutual funds, ETFs, closed-end funds, and UCITS vehicles.

"Thornburg has a long history of delivering differentiated, actively managed strategies, and we're proud to support the continued evolution of their ETF platform," said Donna Milrod, chief product officer at State Street.

Mark Zinkula, CEO of Thornburg, said State Street's experience across fund structures positions the firm to help meet evolving client needs.

State Street operates with $53.8 trillion in assets under custody and administration and $5.7 trillion in assets under management as of December 31, 2025. The company employs approximately 52,000 people worldwide across more than 100 geographic markets.