An expanding online security company has leased 19,300 square feet at 75-101 Federal St. in Boston’s Financial District.

San Diego-based iBoss Cybersecurity opened its first Boston office last March, five months after raising $35 million from Goldman Sachs.

Rockpoint Group of Boston acquired the 31-story, 564,000-square-foot office complex in 2015 for $326 million. It built out the whole-floor office suite on a speculative basis with the strategy of landing a tenant with immediate expansion needs.

Rockpoint recently completed renovations to the towers’ lobby, construction of an 8,500-square-foot second-floor fitness center and model suite. In the lobby, Shawmut Construction oversaw installation of an oversized custom clock behind the reception desk and new terrazzo flooring.

Cushman & Wakefield’s Brian Hines and Malcolm See represented iBoss in the iBoss transaction. Newmark Grubb Knight Frank’s Dave Martel, Tim Bianchi and Ali Cavanaugh represented the landlord.