Bupa is moving its global headquarters to Angel Court, a new City block that was completed in February.
The healthcare company is moving from its current base in Holborn and will be leasing 56,000 square feet (sq ft) in the lower two floors at Angel Court for a period of 15 years.
Mitsui Fudosan UK and Stanhope also announced today they have agreed two additional leases on the building, which is providing 300,000 sq ft of space in total.
The new trade association that is being formed by the British Bankers' Association, the Council of Mortgage Lenders, and others, will also be joining Bupa. The group, which does not yet have a name, will be taking up 25,000 sq ft on the fifth floor of Angel Court in July.
And, on the 19th floor, the Chinese commercial bank Shanghai Pudong Development Bank will be taking up 9,000 sq ft.
Angel Court is one of three large office buildings that open this year. The Scalpel, near the iconic Lloyd's of London building, and 45 Cannon Street, are both expected to open their doors.
Eiichiro Onozawa, managing director of Mitsui Fudosan, said: "These significant first lettings at Angel Court are a clear testament to the attractive, high quality accommodation we have delivered in the heart of one of the world's most competitive and high-profile business centres.
"This building demonstrates our commitment over the long term to invest in and develop prime schemes across London, which cater to the evolving occupier market and set the bar for all developments which follow."