Equity Office Properties Trust said independent proxy advisory firm Institutional Shareholder Services has recommended its shareholders approve BlackstoneGroup's raised merger offer of $54 a share.
The all-cash offer, which was increased last Thursday, values Equity Office at $22.4 billion, which would make it one of the largest private-equity buyouts ever.
Equity Office, the largest publicly traded owner and manager of U.S. office properties, said its common shareholders are scheduled to vote on the merger on Feb 5.
Blackstone's latest offer represents an increase of $5.50 a share over its previous, $48.50 a share offer made on Nov. 19, Equity Office said.
Competing bidder Vornado Group has until Jan 31 to make a new offer to top its existing $52 cash and shares bid, it added. Vornado's offer totals $21.6 billion. The group includes Barry Sternlicht of Starwood Capital Group Global and Neil Bluhm of Walton Street Capital.
Founded by real estate magnate Sam Zell in 1976, Equity Office in 2001 became the first REIT to join the Standard & Poor's 500 index.