Real estate investment trust Hammerson has acquired a 999-year leasehold interest in a prime London location for £100m, including costs.The company, which operates primarily in the retail sector - owning well-known shopping centres such as Brent Cross in London and the Bullring in Birmingham - announced on Friday that it has purchased a virtual freehold interest in 99 Bishopsgate from PRUPIM, acting on behalf of the Prudential Assurance Company.The 26-storey tower, situated near Liverpool Street Station, consists of 31,500m squared of office accommodation occupied by companies including Deutsche Bank, Latham & Watkins and Korea Development Bank."This freehold acquisition further increases our exposure to the City of London office market whilst improving asset liquidity and expected returns. 99 Bishopsgate is an excellent building which has consistently achieved peak City rents. We have an exciting business plan for the property and ownership of the merged interest will ensure that we maximise returns to shareholders from this investment," said chief executive David Atkins.The firm's shares fell almost 5% lower on Thursday after its largest shareholder, a unit of the Ontario Teachers' Pension Plan, sold its entire 12% stake in the company at 463 pence a share.BC