In the first deal, signature tenant Mellon Financial Corp. agreed to lease an additional 44,000 sf of space for 10 years. The pact is valued at about $12.5 million.

New York-based Mellon Financial already occupies two full floors in the 26-story tower, at 400 S. Hope St., as well as some ground-floor space. The additional 44,000 sf will raise its total space in the building to more than 103,000 sf.

The second lease calls for O'Melveny & Myers LLP, one of the nation's largest law firms, to take an additional 30,500 sf at the development. The lease pushes O'Melveny's tenancy at the building to 295,000 sf.

Financial terms of the law firm's lease weren't disclosed. O'Melveny controls 400 South Hope Street Associates, the private investment group that owns the 662,000-sf skyscraper.

CB Richard Ellis, which has managed the complex since 1995, says that the pair of new leases means that the building is now fully occupied even though Downtown's overall office vacancy factor hovers near 20%. Brokers from Jones Lang LaSalle represented Mellon in its lease negotiations.