A month after announcing it was moving its headquarters from Chicago to Miami, multinational hedge fund and financial services company Citadel has made it official by signing a 90,000-square-foot lease at Miami’s most expensive office tower.

The 55-story building, 830 Brickell, is proving popular among major tech and finance companies moving to or expanding in Miami. Though it’s yet to be completed, its tenants already include Microsoft Corp., CI Financial, Marsh Insurance, aircraft leasing company AerCap, private equity firm Thoma Bravo and New York-based insurance firm A-CAP.