The future owner of Equity Office Properties Trust (EOP) is still in doubt. Yesterday, Vornado Realty Trust offered to pay $41 billion for the sprawling office REIT. This latest offer comes just days after the original buyer, Blackstone Group, proposed to pay $38.3 billion for EOP. Blackstone has stated that it has no plans to raise its all-cash offer.

The private equity firm has also said that unlike Vornado, which is offering a mixed cash/stock offer that equals roughly $56 per EOP share, Blackstone could close the deal by February 8. The Vornado offer must be approved by shareholders of the Manhattan-based diversified REIT (VNO).

VNO clearly sees the lure of a quick closing as vital. Yesterday, VNO claimed in a letter to EOP chairman Sam Zell that “a substantial percentage” of investors have voted in favor of the sweetened offer. The VNO offer consists of $31 in cash and $25 in VNO stock. VNO also applied what’s called a “collar” on their bid.

The collar fixes the offer’s value at $56 per share provided that the REIT’s stock doesn’t drop below $115 or exceed $135 per share. If the value of the stock takes a precipitous drop, that would naturally decrease the value of the VNO offer. Shares in VNO were trading around $126 this morning, up 0.21% for the day.

According to the VNO Web site, roughly $20 billion of the EOP portfolio would be sold during the 12 months following a successful sale. As much as $10 billion of that total would also be sold immediately to VNO’s partners on the deal, Starwood Capital Group and Walton Street Capital, two private real estate firms.

If EOP accepts the higher offer from VNO, it will also pay a $500 million breakup fee to Blackstone. The original breakup fee was $200 million, but Blackstone raised it earlier this week to $500 million as a way to defend the deal from VNO.

We’d like to hear your thoughts on this developing story. Email parke.chapman@penton.com.