Office manager Investa Office Fund is subject of a $3.14 billion cash bid from US private equity group Blackstone. : Office manager Investa Office Fund is subject of a $3.14 billion cash bid from US private equity group Blackstone. The ASX-listed firm says Blackstone has offered $5.25 a share, which, adjusted for any full-year distribution, represents a 13 per cent premium to Friday's closing price of $4.55. Investa said it received an initial confidential proposal of $5.05 a share on April 5, and negotiated the improved proposal that it received on May 4.