State Street, the Boston-based banking and financial services group, will provide investment manager operations outsourcing services for approximately $300 billion in assets for Morgan Stanley Investment Management, the two firms said yesterday.

State Street will absorb 100 employees from the Morgan Stanley unit as part of the deal, according to a statement from the firms.

A major provider of financial services to institutional investors, State Street will handle trade settlement, portfolio administration and reporting and reconciliation services for a majority of MSIM’s assets under management. The two firms have been working together for four decades.

“We are very pleased to expand upon our long-standing partnership with State Street to ensure that MSIM remains well-positioned to deliver best-in-class investment operations and technology solutions to our investment teams and our clients,”  Joanne Pace, chief operating officer of Morgan Stanley Investment Management, said.