The Spanish unit of real estate group Carso, which is owned by Mexican billionaire Carlos Slim, purchased 439 properties for $563.7 million from Spain's CaixaBank, the Spanish financial institution said in a filing with stock market regulator CNMV on Tuesday.

CaixaBank signed long-term leases, with purchase options, with the buyer for the buildings, which house bank branches.

The financial institution expects to book a gain on the deal.

The buyer, Inmobiliaria Carso, is a unit of Grupo Carso, one of the largest conglomerates in Latin America.

Grupo Carso has interests in the industrial, retail, infrastructure, construction and automotive sectors.

Grupo Carso is owned by Slim, who is ranked by Forbes magazine as the world's richest person.

Slim, a shareholder in CaixaBank, controls, among other companies, telecom giant Telmex. EFE