Qatar already has a 27.7% stake in Songbird, the majority owner of Canary Wharf   Doha - Arabstoday Qatar\'s sovereign wealth fund Qatar Investment Authority (QIA) said it had completed the acquisition of Credit Suisse\'s headquarters in London and leased it back to the bank. The 546,114 square-feet building at One Cabot Square in Canary Wharf was leased to  the bank under a long-term agreement that runs until 2034, Qatar Holding, the foreign investment arm of QIA said in a statement on its website on Monday. The value of the deal was not disclosed. The authority was to pay 330m pounds ($517m) for the property, with a separate leaseback agreement to be put in place with the Swiss lender, two sources told Reuters last month. QIA holds a 6 percent stake in Credit Suisse and owns shares in Songbird, the majority owner of Canary Wharf Group. Gulf-government backed funds have been on a buying spree in Europe and are eyeing investments in real estate, infrastructure and other sectors. Qatari Diar, a property arm of the fund, along with Canary Wharf, won a 300m-pound deal to redevelop the Shell Centre in London that houses the Royal Dutch Shell\'s London headquarters in July. Qatar has other high-profile investments in London, including the U.S. embassy in Grosvenor Square and Harrods department store.