The fund, known as Istithmar, will provide the developer, Related Cos., with a $75-million equity investment in the project, about a quarter of the capital needed to secure a construction loan.

A previous investor, California Public Employees' Retirement System, pulled out last year after deciding with its advisor, the investment firm MacFarlane Partners, that it was significantly invested in other downtown projects, including L.A. Live, 1100 Wilshire and the Metropolitan Lofts.

Because its investment in the project is significant, Istithmar must be approved by the city and county and by a joint city-county board overseeing the development before construction can begin. Officials for Related say they expect to receive approval next month and begin construction this summer.