Mirvac to sell stake in Westpac tower Mirvac is expected to realise about $450m for the sale of a half-stake in the Westpac building in Kent St, Sydney. Picture: Brad Hunter. THE offer of a half-stake in Mirvac Group's $900 million Westpac Place is expected to set a bullish tone for office tower values this year, with the competition for assets rising as property investors jostle for stock. The impending takeover of the Commonwealth Property Office Fund by a Dexus Property Group consortium has prompted concerns that relatively few major towers will come on to the market and those that do will be fiercely contested. The offer of the building at this time -- several years after Mirvac picked it up by acquiring the Westpac Office Trust -- also points to its belief that values have lifted. Mirvac group's agents -- Josh Cullen and Michael Andrews of CBRE and Rob Sewell, Paul Noonan and Simon Storry of Jones Lang LaSalle -- are understood to be about to embark on an international roadshow to offer the stake in the tower, which is expected to fetch about $450m. The tower, which serves as Westpac's Sydney headquarters and was purpose-built for the bank, is one of the first of the new-generation office buildings that investors are now chasing. Despite the bank's commitment to anchoring a new tower in Lend Lease's Barangaroo South office precinct, bank chief executive Gail Kelly last year underlined the bank's commitment to staying in the tower at Kent Street, Sydney. The stake in the Westpac tower -- which had been earmarked for Mirvac's office club but attracted significant interest as a stand-alone asset -- could become one of the first office assets to change hands on a yield of less than 6 per cent after the global financial crisis. The top end of the office market has been running hot, with superannuation-backed giant ISPT buying a half-share in Brisbane's 1 William Street office tower development from Cbus Property for almost $400m on a tight yield in the low 6 per cent range. Leighton Properties pre-sold a North Sydney tower for $413.19m to Singapore's Suntec REIT on a 6.89 per cent yield. Mirvac, which is pursuing separate funds management plans for newer office projects, is likely to pour the sale proceeds into its expanding office and residential development pipeline.